EP0475288A1 - Plasma jet ignition system - Google Patents

Plasma jet ignition system Download PDF

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Publication number
EP0475288A1
EP0475288A1 EP91115063A EP91115063A EP0475288A1 EP 0475288 A1 EP0475288 A1 EP 0475288A1 EP 91115063 A EP91115063 A EP 91115063A EP 91115063 A EP91115063 A EP 91115063A EP 0475288 A1 EP0475288 A1 EP 0475288A1
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EP
European Patent Office
Prior art keywords
cavity
ignition
electrodes
plasma jet
ignition system
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Granted
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EP91115063A
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German (de)
French (fr)
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EP0475288B1 (en
Inventor
Herbert Prof. Dr.-Ing Wilhelmi
Franz Prof. Dr. Pischinger
Gerhard Dr.-Ing. Lepperhoff
Peter Dipl.-Ing. Wefels
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FEV Europe GmbH
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FEV Motorentechnik GmbH and Co KG
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    • H—ELECTRICITY
    • H01—ELECTRIC ELEMENTS
    • H01T—SPARK GAPS; OVERVOLTAGE ARRESTERS USING SPARK GAPS; SPARKING PLUGS; CORONA DEVICES; GENERATING IONS TO BE INTRODUCED INTO NON-ENCLOSED GASES
    • H01T13/00—Sparking plugs
    • H01T13/50—Sparking plugs having means for ionisation of gap

Definitions

  • the invention relates to a plasma jet ignition system for internal combustion engines with ignition energies of less than 200 mJ with a hollow insulator body which is open to the combustion chamber and at least two electrodes projecting into this cavity and / or the opening thereof.
  • the present invention has for its object to provide a plasma jet ignition system that easily achieves both a high ignition power and a high energy density of the plasma jet and thus safely avoids the disadvantages of coil ignition systems and conventional plasma jet igniters.
  • Ignition systems in which the plasma jet is formed in a cavity are known.
  • a disadvantage of these devices is that, due to the arrangement of the electrodes in the cavity of the igniter, the spark channel is formed along the cavity wall. This so-called sliding spark formation is even considered an advantage, e.g. in DE 3816968, DE 3533124 and DE 3533123. Despite the short time of the spark breakdown, energy losses occur at the cavity surface during the formation of sliding sparks.
  • arrangements with small void volumes per ignition energy unit and spark plug electrodes with small ignition energy advantageously enable the ignition spark to form in the void volume without wall contact.
  • This effect is achieved by the position of the two electrodes relative to one another and to the cavity-forming surfaces. Due to the minimal heat loss, a plasma jet with a high energy density is formed. This advantageously increases the amount of energy transferred to the mixture with the possibility of significantly higher emaciation of the fuel / air mixture.
  • the cavity volume per ignition energy unit is less than 6.5 mm 3 / mJ, that the ignition channel formed between these electrodes runs centrally or almost centrally through the cavity, and that the ignition channel end points at the electrode ends facing each other are separated from one another by a shorter air gap than the distance between the ignition channel end points and the surface of the cavity.
  • the optimal range can be 1 - 1.6 mm 3 / mJ.
  • the outlet opening of the cavity has a lateral recess or recess for receiving at least one second electrode. It can also be expedient that the outlet opening of the cavity has at least two symmetrically or asymmetrically arranged side niches or recesses for receiving at least one second electrode each. In this way, a reduction in the volume of the cavity forming the plasma and thus an increase in the energy density while avoiding sliding spark formation is advantageously achieved.
  • the cross section of the laterally protruding second electrode or the laterally protruding electrodes decreases over the length of the electrode or the electrodes. It may also be expedient for the electrodes to be provided with a heat-resistant electrical insulation layer in such a way that sparks are avoided along the surface of the cavity.
  • a cavity 10 is formed on the front side of the igniter facing the combustion chamber of an internal combustion engine (not shown), the lateral boundary of which represents the inner lateral surface of a hollow insulator body 11.
  • the insulator body 11 surrounds an electrically conductive first electrode 12, the conical tip 16 of which is directed towards the combustion chamber.
  • An electrically conductive second electrode 13 is arranged in the region of the outlet opening 21 of the cavity 10, so that an electrical spark discharge can take place in a gas volume of the cavity 10 separated from the combustion chamber.
  • the inner diameter 22 of the insulator body 11 is approximately 30-70% smaller than the outer diameter of the igniter housing.
  • the electrodes 12 and 13 are advantageously arranged geometrically such that the air gap between the tip 16 of the electrode 12 and the surface of the cavity 10 is greater than the free distance 24 between the electrodes 12 and 13 and the location of the minimum distance between the electrodes 12 and 13 in the cavity 10 near the central axis of the igniter. This ensures that the ignition channel runs centrally through the cavity 10.
  • the center electrode 12 will generally be cylindrical in shape and may taper into a conical tip 16 as shown in FIG. 1. It can e.g. also be hemispherical at its end as shown in FIG. 2.
  • the cavity 10 will generally be rotationally symmetrical and, as shown in FIG. 1, it may have a cylindrical shape 15. However, it can also be expedient for the cavity 10 to have a conical shape 19, as shown in FIG. 2, or a nozzle shape 20, as is shown in FIG. 3.
  • the outlet opening 21 of the cavity 10 can also have a larger radius than the smallest cavity radius at the point 22. It can also be advantageous that the distance 14 between the electrode 13 and the end of the outlet opening 21 of the cavity 10 is less than 10 mm .
  • the electrodes 12 and 13 are provided with a heat-resistant electrical insulation layer in such a way that sparks are avoided along the surface of the cavity 10.
  • the electrodes 13 can not only be cylindrical, but also conical or in some other way. Particular advantages can be achieved if the electrodes 13 have a cross-section which decreases over their free length, for example ending in a tip, since this stabilizes the spark breakdown.
  • the cavity 10 is essentially cylindrical, but the electrode 13 is located in a recess or recess 25 in the wall of the space 10.
  • the smallest inside diameter 22 of the insulator body 11 is 30-70% smaller than the outside diameter of the housing 23 enables an electrical spark discharge to take place in a gas volume of the cavity 10 separated from the combustion chamber, the outlet cross section not being impaired by internals.
  • Several niches or recesses 25 with electrodes 13 can also be arranged symmetrically or asymmetrically.
  • a particular advantage of the described plasma jet ignition system is that the spark is generated centrally or almost centrally in a cavity which is very small in relation to the combustion chamber.
  • the high energy density after sparking causes an increase in pressure in the cavity (pressures of around 300 bar and temperatures of up to 60,000 degrees Kelvin can occur in the ignition channel), which leads to the escape of very high-energy molecules. These molecules meet flammable gas mixtures outside the igniter so that the ignition takes place without contacting electrodes.
  • a major advantage of the invention is the avoidance of heat dissipation during spark breakdown. A reduction in the energy transmission of the spark to the fuel / air medium is thus avoided, as is the energy loss at the electrodes in the case of the ignited fuel / air mixture in the vicinity of the electrodes.
  • a free plasma jet protruding into the fuel / air mixture is generated, which reliably ignites the surrounding fuel / air mixture due to its high temperature and high energy. Since the plasma jet is caused by the release of an electrically stored energy, which mainly takes place in the breakdown phase of the spark discharge and minimizing wall heat losses, the efficiency of the ignition energy transfer to the mixture is especially high.
  • the ignition can be achieved with extremely small primary energies in the order of magnitude of only about 30-300 mJ, so that the ignition system can also be used advantageously for vehicle engines. Another advantage is that with these small primary energies there is very little erosion on the electrodes.

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  • Ignition Installations For Internal Combustion Engines (AREA)

Abstract

In a plasma jet ignition system for internal-combustion engines, having ignition energies of less than 200 mJ, having an insulator body (11), which is open towards the combustion chamber of the internal-combustion engine and is of hollow shape, and having at least two electrodes (12, 13), which project into the cavity (10) of the insulator body (11) and/or its opening, it is provided that the volume of the cavity (10) per unit of ignition energy is less than 6.5 mm<3>/mJ, that the ignition channel formed between the electrodes runs centrally or virtually centrally through the cavity (10), and that the end points of the ignition channel are separated from one another at the ends of the electrodes (12, 13) pointing towards one another by an air gap which is shorter than the distance of the end points of the ignition channel from the surface of the cavity (10). <IMAGE>

Description

Die Erfindung bezieht sich auf ein Plasmastrahl-Zündsystem für Verbrennungskraftmaschinen mit Zündenergien kleiner als 200 mJ mit einem zum Brennraum offenen, hohl geformten Isolatorkörper und mindestens zwei in diesen Hohlraum und/oder deren Öffnung ragenden Elektroden.The invention relates to a plasma jet ignition system for internal combustion engines with ignition energies of less than 200 mJ with a hollow insulator body which is open to the combustion chamber and at least two electrodes projecting into this cavity and / or the opening thereof.

Zur Entzündung von Kraftstoff/Luft-Gemischen werden in Ottomotoren fast ausnahmslos Spulenzündanlagen mit konventionellen Zündkerzen verwendet. Bei diesen Systemen erfolgt die Freisetzung der elektrisch gespeicherten Zündenergie zum überwiegenden Teil in Form einer Glimmentladung, die den Nachteil hat, daß relativ hohe Wärmeverluste an den Zündkerzenelektroden auftreten. Da die Bildung von Flammenkernen nur in unmittelbarer Nähe der Zündkerzenelektroden stattfindet, ist ein partielles Auslöschen des Flammenkerns durch den Kontakt mit den relativ kalten Zündkerzenelektroden unvermeidbar.Almost without exception, coil ignition systems with conventional spark plugs are used in gasoline engines to ignite fuel / air mixtures. In these systems, the release of the electrically stored ignition energy takes place predominantly in the form of a glow discharge, which has the disadvantage that relatively high heat losses occur at the spark plug electrodes. Since the formation of flame cores only takes place in the immediate vicinity of the spark plug electrodes, partial extinguishing of the flame core by contact with the relatively cold spark plug electrodes is unavoidable.

Die Ausbreitung des Flammenkerns zu einer stabilen Flamme erfordert ein genügend großes, die Zündkerzenelektroden umgebendes zündfähiges Gemischvolumen. Dies große zündfähige Gemischvolumen ist auch bei Vorkammer- oder Fakkelzündkerzen durch einen großen Hohlraum in der Zündkerze sicherzustellen. Kleine Hohlraumvolumina lassen die Flamme infolge Energieverlusten an der Wand ausgehen.The spreading of the flame core to a stable flame requires a sufficiently large ignitable mixture volume surrounding the spark plug electrodes. This large ignitable mixture volume must also be ensured for prechamber or fake spark plugs by means of a large cavity in the spark plug. Small cavity volumes let the flame go out due to energy losses on the wall.

Nachteile dieser Art können durch Plasmastrahl-Zündsysteme mit hohem Übertragungswirkungsgrad behoben werden. Der Vorgang der elektrischen Zündenergieentladung findet bei Systemen dieser Art zum überwiegenden Teil während des Funkendurchbruchs statt, der in einer Zeitspanne von nur ca. 50 nsec erfolgt, so daß höhere Zündleistungen erreicht werden als bei Zündsystemen herkömmlicher Art.Disadvantages of this type can be remedied by plasma jet ignition systems with high transmission efficiency. The process of electrical ignition energy discharge takes place in systems of this type for the most part during the spark breakdown, which takes place in a period of only about 50 nsec, so that higher ignition powers are achieved than with ignition systems of conventional type.

Der vorliegenden Erfindung liegt die Aufgabe zugrunde, ein Plasmastrahl-Zündsystem zu schaffen, das in einfacher Weise sowohl eine hohe Zündleistung als auch eine hohe Energiedichte des Plasmastrahls erreicht und so die Nachteile von Spulenzündsystemen und herkömmlichen Plasmastrahlzündern in sicherer Weise vermeidet.The present invention has for its object to provide a plasma jet ignition system that easily achieves both a high ignition power and a high energy density of the plasma jet and thus safely avoids the disadvantages of coil ignition systems and conventional plasma jet igniters.

Zündsysteme, bei denen die Plasmastrahl-Bildung in einem Hohlraum erfolgt, sind bekannt. Bei diesen Einrichtungen ist nachteilig, daß aufgrund der Elektrodenanordnung im Hohlraum des Zünders die Funkenkanalbildung entlang der Hohlraumwand erfolgt. Diese sogenannte Gleitfunkenbildung wird sogar als Vorteil angesehen, z.B. in DE 3816968, DE 3533124 und DE 3533123. Trotz der kurzen Zeit des Funkendurchbruchs treten bei der Gleitfunkenbildung Energieverluste an der Hohlraumoberfläche auf.Ignition systems in which the plasma jet is formed in a cavity are known. A disadvantage of these devices is that, due to the arrangement of the electrodes in the cavity of the igniter, the spark channel is formed along the cavity wall. This so-called sliding spark formation is even considered an advantage, e.g. in DE 3816968, DE 3533124 and DE 3533123. Despite the short time of the spark breakdown, energy losses occur at the cavity surface during the formation of sliding sparks.

Bei der vorliegenden Erfindung ist demgegenüber bei Anordnungen mit kleinen Hohlraumvolumen pro Zündenergieeinheit und Zündkerzenelektroden mit kleiner Zündenergie (≤ 200 mJ) in vorteilhafter Weise ermöglicht, daß sich der Zündfunke im Hohlraumvolumen ohne Wandkontakt ausbilden kann. Dieser Effekt wird durch die Lage der beiden Elektroden zueinander sowie zu den hohlraumbildenden Oberflächen erreicht. Aufgrund der minimalen Wärmeverluste wird ein Plasmastrahl mit einer hohen Energiedichte gebildet. Damit steigt in vorteilhafter Weise die an das Gemisch übertragene Energiemenge mit der Möglichkeit deutlich höherer Abmagerung des Kraftstoff/Luftgemisches.In contrast, in the case of the present invention, arrangements with small void volumes per ignition energy unit and spark plug electrodes with small ignition energy (200 200 mJ) advantageously enable the ignition spark to form in the void volume without wall contact. This effect is achieved by the position of the two electrodes relative to one another and to the cavity-forming surfaces. Due to the minimal heat loss, a plasma jet with a high energy density is formed. This advantageously increases the amount of energy transferred to the mixture with the possibility of significantly higher emaciation of the fuel / air mixture.

Gemäß der Erfindung ist bei einem Plasmastrahl-Zündsystem der eingangs bezeichneten Art vorgesehen, daß das Hohlraumvolumen pro Zündenergieeinheit kleiner als 6,5 mm3/mJ ist, daß der zwischen diesen Elektroden sich ausbildende Zündkanal zentral oder nahezu zentral durch den Hohlraum verläuft, und daß die Zündkanalendpunkte an den zueinander gerichteten Elektrodenenden voneinander durch einen kürzeren Luftspalt getrennt sind als der Abstand der Zündkanalendpunkte zur Oberfläche des Hohlraumes. Der optimale Bereich kann 1 - 1,6 mm3/mJ sein.According to the invention it is provided in a plasma jet ignition system of the type mentioned that the cavity volume per ignition energy unit is less than 6.5 mm 3 / mJ, that the ignition channel formed between these electrodes runs centrally or almost centrally through the cavity, and that the ignition channel end points at the electrode ends facing each other are separated from one another by a shorter air gap than the distance between the ignition channel end points and the surface of the cavity. The optimal range can be 1 - 1.6 mm 3 / mJ.

Gemäß einer bevorzugten Ausführungsform ist vorgesehen, daß die Austrittsöffnung des Hohlraumes eine seitliche Nische oder Aussparung zur Aufnahme von wenigstens einer zweiten Elektrode aufweist. Auch kann es zweckmäßig sein, daS die Austrittsöffnung des Hohlraumes wenigstens zwei symmetrisch oder asymmetrisch angeordnete seitliche Nischen oder Aussparungen zur Aufnahme von wenigstens je einer zweiten Elektrode aufweist. Hierdurch wird eine Verringerung des das Plasma bildenden Hohlraumvolumens und damit eine Erhöhung der Energiedichte unter Vermeidung von Gleitfunkenbildung in vorteilhafter Weise erreicht.According to a preferred embodiment it is provided that the outlet opening of the cavity has a lateral recess or recess for receiving at least one second electrode. It can also be expedient that the outlet opening of the cavity has at least two symmetrically or asymmetrically arranged side niches or recesses for receiving at least one second electrode each. In this way, a reduction in the volume of the cavity forming the plasma and thus an increase in the energy density while avoiding sliding spark formation is advantageously achieved.

Gemäß einem weiteren bevorzugten Merkmal ist vorgesehen, daß der Querschnitt der seitlich vorragenden zweiten Elektrode bzw. der seitlich vorragenden Elektroden über die Länge der Elektrode bzw. der Elektroden abnimmt. Auch kann es zweckmäßig sein, daß die Elektroden mit einer wärmebeständigen elektrischen Isolationsschicht versehen sind, derart, daß eine Ausbildung von Funken entlang der Oberfläche des Hohlraums vermieden ist.According to a further preferred feature, it is provided that the cross section of the laterally protruding second electrode or the laterally protruding electrodes decreases over the length of the electrode or the electrodes. It may also be expedient for the electrodes to be provided with a heat-resistant electrical insulation layer in such a way that sparks are avoided along the surface of the cavity.

Hinsichtlich weiterer vorteilhafter Merkmale der Erfindung wird auf die nachfolgende Beschreibung und die Ansprüche Bezug genommen.With regard to further advantageous features of the invention, reference is made to the following description and the claims.

Ausführungsbeispiele der Erfindung werden anhand der Zeichnungen näher beschrieben.

  • Fig. 1, 2 und 3 zeigen in schematischer Schnittdarstellung Einzelheiten von Ausführungsformen des Plasmastrahl-Zünders gemäß der Erfindung.
  • Fig. 4 zeigt in Draufsicht die Anordnung mehrerer Elektroden in der Austrittsöffnung des Hohlraums.
  • Fig. 5 zeigt in schematischer Schnittdarstellung eine weitere vorteilhafte Ausführungsform.
Embodiments of the invention are described in more detail with reference to the drawings.
  • 1, 2 and 3 show a schematic sectional illustration of details of embodiments of the plasma jet igniter according to the invention.
  • Fig. 4 shows a top view of the arrangement of several electrodes in the outlet opening of the hollow space.
  • 5 shows a further advantageous embodiment in a schematic sectional illustration.

Fig. 1 zeigt als erste Ausführungsform eine Einzelheit des Plasmastrahl-Zündsystems gemäß der Erfindung. An der dem Brennraum einer (nicht dargestellten) Verbrennungskraftmaschine zugewandten Stirnseite des Zünders ist ein Hohlraum 10 ausgebildet, dessen seitliche Begrenzung die innere Mantelfläche eines hohlen Isolatorkörpers 11 darstellt. Der Isolatorkörper 11 umgibt eine elektrisch leitende erste Elektrode 12, deren konische Spitze 16 zum Brennraum gerichtet ist. Im Bereich der Austrittsöffnung 21 des Hohlraumes 10 ist eine elektrisch leitende zweite Elektrode 13 angeordnet, so daß eine elektrische Funkenentladung in einem Gasvolumen des vom Brennraum abgetrennten Hohlraums 10 stattfinden kann. Der Innendurchmesser 22 des Isolatorkörpers 11 ist etwa 30-70% kleiner als der Außendurchmesser des Zündergehäuses.1 shows as a first embodiment a detail of the plasma jet ignition system according to the invention. A cavity 10 is formed on the front side of the igniter facing the combustion chamber of an internal combustion engine (not shown), the lateral boundary of which represents the inner lateral surface of a hollow insulator body 11. The insulator body 11 surrounds an electrically conductive first electrode 12, the conical tip 16 of which is directed towards the combustion chamber. An electrically conductive second electrode 13 is arranged in the region of the outlet opening 21 of the cavity 10, so that an electrical spark discharge can take place in a gas volume of the cavity 10 separated from the combustion chamber. The inner diameter 22 of the insulator body 11 is approximately 30-70% smaller than the outer diameter of the igniter housing.

Die Elektroden 12 und 13 sind in vorteilhafter Weise geometrisch derart angeordnet, daß der Luftspalt zwischen der Spitze 16 der Elektrode 12 und der Oberfläche des Hohlraums 10 größer als der freie Abstand 24 zwischen den Elektroden 12 und 13 ist und die Stelle des Mindestabstandes zwischen den Elektroden 12 und 13 im Hohlraum 10 in der Nähe der Mittelachse des Zünders liegt. Dadurch ist sichergestellt, daß der Zündkanal zentral durch den Hohlraum 10 verläuft.The electrodes 12 and 13 are advantageously arranged geometrically such that the air gap between the tip 16 of the electrode 12 and the surface of the cavity 10 is greater than the free distance 24 between the electrodes 12 and 13 and the location of the minimum distance between the electrodes 12 and 13 in the cavity 10 near the central axis of the igniter. This ensures that the ignition channel runs centrally through the cavity 10.

Die Anordnung kann den jeweiligen Anforderungen und Betriebsverhältnissen in vorteilhafter Weise angepaßt werden. So wird die Mittelelektrode 12 im allgemeinen eine zylindrische Form haben, und sie kann entsprechend der Darstellung in Fig. 1 in eine konische Spitze 16 auslaufen. Sie kann z.B. auch entsprechend der Darstellung in Fig. 2 an ihrem Ende halbkugelförmig ausgebildet sein.The arrangement can be adapted to the respective requirements and operating conditions in an advantageous manner. For example, the center electrode 12 will generally be cylindrical in shape and may taper into a conical tip 16 as shown in FIG. 1. It can e.g. also be hemispherical at its end as shown in FIG. 2.

Der Hohlraum 10 wird im allgemeinen rotationssymmetrisch ausgebildet sein, und er kann entsprechend der Darstellung in Fig. 1 eine zylindrische Form 15 haben. Es kann jedoch auch zweckmäßig sein, daß der Hohlraum 10 eine konische Form 19 hat, wie Fig. 2 zeigt, oder eine Düsenform 20, wie es in Fig. 3 dargestellt ist. Dabei kann auch die Austrittsöffnung 21 des Hohlraums 10 einen größeren Radius aufweisen als der kleinste Hohlraumradius an der Stelle 22. Auch kann es vorteilhaft sein, daß der Abstand 14 zwischen der Elektrode 13 und dem Ende der Austrittsöffnung 21 des Hohlraums 10 kleiner als 10 mm ist.The cavity 10 will generally be rotationally symmetrical and, as shown in FIG. 1, it may have a cylindrical shape 15. However, it can also be expedient for the cavity 10 to have a conical shape 19, as shown in FIG. 2, or a nozzle shape 20, as is shown in FIG. 3. The outlet opening 21 of the cavity 10 can also have a larger radius than the smallest cavity radius at the point 22. It can also be advantageous that the distance 14 between the electrode 13 and the end of the outlet opening 21 of the cavity 10 is less than 10 mm .

Besondere Vorteile sind erreichbar, wenn die Elektroden 12 und 13 mit einer wärmebeständigen elektrischen Isolationsschicht derart versehen sind, daß eine Ausbildung von Funken entlang der Oberfläche des Hohlraums 10 vermieden wird.Particular advantages can be achieved if the electrodes 12 and 13 are provided with a heat-resistant electrical insulation layer in such a way that sparks are avoided along the surface of the cavity 10.

Fig. 4 zeigt in Draufsicht die Anordnung mehrerer Elektroden 13 im Gehäuse 23, wobei im vorliegenden Fall vier Elektroden 13 sich bei der gewählten Darstellung vor der Elektrode 12 befinden. Die Elektroden 13 können dabei nicht nur zylindrisch, sondern auch konisch oder in anderer Weise ausgebildet sein. Besondere Vorteile sind erreichbar, wenn die Elektroden 13 einen über ihre freie Länge abnehmenden Querschnitt haben, beispielsweise in einer Spitze enden, da hierdurch der Funkendurchbruch stabilisiert wird.4 shows a top view of the arrangement of a plurality of electrodes 13 in the housing 23, four electrodes 13 being located in front of the electrode 12 in the selected illustration in the present case. The electrodes 13 can not only be cylindrical, but also conical or in some other way. Particular advantages can be achieved if the electrodes 13 have a cross-section which decreases over their free length, for example ending in a tip, since this stabilizes the spark breakdown.

Fig. 5 zeigt vereinfacht und im Längsschnitt eine weitere bevorzugte Ausführungsform. Der Hohlraum 10 ist im wesentlichen zylindrisch ausgebildet, jedoch befindet sich die Elektrode 13 in einer Nische oder Aussparung 25 der Wandung des Raumes 10. Der kleinste Innendurchmesser 22 des Isolatorkörpers 11 ist dabei 30-70% kleiner als der Außendurchmesser des Gehäuses 23. Dadurch ist ermöglicht, daß eine elektrische Funkenentladung in einem Gasvolumen des vom Brennraum getrennten Hohlraumes 10 stattfinden kann, wobei der Austrittsquerschnitt nicht durch Einbauten beeinträchtigt ist. Es können auch mehrere Nischen oder Aussparungen 25 mit Elektroden 13 symmtrisch oder asymmetrisch angeordnet sein.5 shows a simplified and longitudinal section of a further preferred embodiment. The cavity 10 is essentially cylindrical, but the electrode 13 is located in a recess or recess 25 in the wall of the space 10. The smallest inside diameter 22 of the insulator body 11 is 30-70% smaller than the outside diameter of the housing 23 enables an electrical spark discharge to take place in a gas volume of the cavity 10 separated from the combustion chamber, the outlet cross section not being impaired by internals. Several niches or recesses 25 with electrodes 13 can also be arranged symmetrically or asymmetrically.

Ein besonderer Vorteil des beschriebenen Plasmastrahl-Zündsystems ist, daß die Funkenbildung zentral oder nahezu zentral in einem Hohlraum erfolgt, der in Relation zum Brennraum sehr klein ist. Die hohe Energiedichte nach der Funkenbildung bewirkt im Hohlraum einen Druckanstieg (in Zündkanal können Drücke von etwa 300 bar und Temperaturen von bis zu 60.000 Grad Kelvin auftreten), der zum Austritt von sehr energiereichen Molekülen führt. Diese Moleküle treffen außerhalb des Zünders auf entzündbare Gasgemische, so daß die Entflammung ohne Kontaktierung von Elektroden abläuft.A particular advantage of the described plasma jet ignition system is that the spark is generated centrally or almost centrally in a cavity which is very small in relation to the combustion chamber. The high energy density after sparking causes an increase in pressure in the cavity (pressures of around 300 bar and temperatures of up to 60,000 degrees Kelvin can occur in the ignition channel), which leads to the escape of very high-energy molecules. These molecules meet flammable gas mixtures outside the igniter so that the ignition takes place without contacting electrodes.

Ein wesentlicher Vorteil der Erfindung ist die Vermeidung einer Wärmeabfuhr beim Funkendurchbruch. Es wird also eine Verminderung der Energieübertragung des Funkens an das Medium Kraftstoff/Luft ebenso vermieden wie der Energieverlust an den Elektroden bei dem entzündeten Kraftstoff/Luft-Gemisch in der Nähe der Elektroden. Bei Anwendung der Erfindung wird ein in das Kraftstoff/Luft-Gemisch hineinragender freier Plasmastrahl erzeugt, der aufgrund seiner hohen Temperatur und seiner hohen Energie das umgebende Kraftstoff/ Luft-Gemisch zuverlässig entzündet. Da der Plasmastrahl durch eine Freisetzung einer elektrisch gespeicherten Energie, die zum überwiegenden Teil in der Durchbruchsphase der Funkenentladung und unter Minimierung von Wandwärmeverlusten erfolgt, hervorgerufen wird, ist der Wirkungsgrad der Zündenergieübertragung an das Gemisch besonders hoch.A major advantage of the invention is the avoidance of heat dissipation during spark breakdown. A reduction in the energy transmission of the spark to the fuel / air medium is thus avoided, as is the energy loss at the electrodes in the case of the ignited fuel / air mixture in the vicinity of the electrodes. When using the invention, a free plasma jet protruding into the fuel / air mixture is generated, which reliably ignites the surrounding fuel / air mixture due to its high temperature and high energy. Since the plasma jet is caused by the release of an electrically stored energy, which mainly takes place in the breakdown phase of the spark discharge and minimizing wall heat losses, the efficiency of the ignition energy transfer to the mixture is especially high.

Bei Anwendung verhältnismäßig hoher Spannungen kann die Zündung mit außerordentlich kleinen Primärenergien in der Größenordnung von nur etwa 30-300 mJ erreicht werden, so daß das Zündsystem in vorteilhafter Weise auch für Fahrzeugmotoren verwendbar ist. Ein weiterer Vorteil ist, daß bei diesen kleinen Primärenergien nur eine sehr geringe Erosion an den Elektroden auftritt.When using relatively high voltages, the ignition can be achieved with extremely small primary energies in the order of magnitude of only about 30-300 mJ, so that the ignition system can also be used advantageously for vehicle engines. Another advantage is that with these small primary energies there is very little erosion on the electrodes.

Claims (6)

1. Plasmastrahl-Zündsystem für Verbrennungskraftmaschinen mit Zündenergien von weniger als 200 mJ mit einem zum Brennraum der Verbrennungskraftmaschine offenen, hohl geformten Isolatorkörper (11) und mindestens zwei in den Hohlraum (10) des Isolatorkörpers (11) und/oder dessen Öffnung ragenden Elektroden (12, 13), dadurch gekennzeichnet, daß das Volumen des Hohlraumes (10) pro Einheit der Zündenergie kleiner als 6,5 mm3/mJ ist, daß der zwischen den Elektroden gebildete Zündkanal zentral oder nahezu zentral durch den Hohlraum (10) verläuft, und daß die Endpunkte des Zündkanals an den zueinander gerichteten Enden der Elektroden (12, 13) voneinander durch einen kürzeren Luftspalt getrennt sind als der Abstand der Endpunkte des Zündkanals zur Oberfläche des Hohlraumes (10).1. Plasma ignition system for internal combustion engines with ignition energies of less than 200 mJ with a hollow-shaped insulator body (11) open to the combustion chamber of the internal combustion engine and at least two electrodes (11) and / or its opening projecting into the cavity (10) of the insulator body (11) 12, 13), characterized in that the volume of the cavity (10) per unit of ignition energy is less than 6.5 mm 3 / mJ, that the ignition channel formed between the electrodes runs centrally or almost centrally through the cavity (10), and that the end points of the ignition channel at the mutually facing ends of the electrodes (12, 13) are separated from one another by a shorter air gap than the distance between the end points of the ignition channel and the surface of the cavity (10). 2. Plasmastrahl-Zündsystem nach Anspruch 1, dadurch gekennzeichnet, daß das Volumen des Hohlraumes (10) pro Zündenergie 1 bis 1,6 mm3/mJ beträgt.2. Plasma jet ignition system according to claim 1, characterized in that the volume of the cavity (10) per ignition energy is 1 to 1.6 mm 3 / mJ. 3. Plasmastrahl-Zündsystem nach Anspruch 1, dadurch gekennzeichnet, daß die Austrittsöffnung (21) des Hohlraumes (10) eine seitliche Nische oder Aussparung (25) zur Aufnahme von wenigstens einer Elektrode (13) aufweist.3. Plasma jet ignition system according to claim 1, characterized in that the outlet opening (21) of the cavity (10) has a lateral recess or recess (25) for receiving at least one electrode (13). 4. Plasmastrahl-Zündsystem nach Anspruch 1, dadurch gekennzeichnet, daß die Austrittsöffnung (21) des Hohlraumes (10) wenigstens zwei symmetrisch oder asymmetrisch angeordnete seitliche Nischen oder Aussparungen (25) zur Aufnahme von wenigstens je einer zweiten Elektrode (13) aufweist.4. Plasma jet ignition system according to claim 1, characterized in that the outlet opening (21) of the cavity (10) has at least two symmetrically or asymmetrically arranged side niches or recesses (25) for receiving at least one second electrode (13). 5. Plasmastrahl-Zündsystem nach Anspruch 1, dadurch gekennzeichnet, daß der Querschnitt einer seitlich vorragenden Elektrode (13) bzw. der seitlich vorragenden Elektroden über die Länge der Elektrode bzw. der Elektroden abnimmt.5. Plasma jet ignition system according to claim 1, characterized in that the cross section of a laterally projecting electrode (13) or the laterally projecting electrodes decreases over the length of the electrode or electrodes. 6. Plasmastrahl-Zündsystem nach Anspruch 1, dadurch gekennzeichnet, daß die Elektroden (12, 13) mit einer wärmebeständigen elektrischen Isolationsschicht versehen sind, derart, daß eine Ausbildung von Funken entlang der Oberfläche des Hohlraums (10) vermieden ist.6. Plasma beam ignition system according to claim 1, characterized in that the electrodes (12, 13) are provided with a heat-resistant electrical insulation layer, such that formation of sparks along the surface of the cavity (10) is avoided.
EP91115063A 1990-09-12 1991-09-05 Plasma jet ignition system Expired - Lifetime EP0475288B1 (en)

Applications Claiming Priority (2)

Application Number Priority Date Filing Date Title
DE4028869 1990-09-12
DE4028869A DE4028869A1 (en) 1990-09-12 1990-09-12 PLASMA JET IGNITION SYSTEM

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EP0475288A1 true EP0475288A1 (en) 1992-03-18
EP0475288B1 EP0475288B1 (en) 1995-01-04

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Cited By (2)

* Cited by examiner, † Cited by third party
Publication number Priority date Publication date Assignee Title
EP2088653A3 (en) * 2008-02-06 2013-05-22 NGK Spark Plug Co., Ltd. Plasma jet ignition plug
US8729782B2 (en) 2010-10-28 2014-05-20 Federal-Mogul Ignition Non-thermal plasma ignition arc suppression

Families Citing this family (6)

* Cited by examiner, † Cited by third party
Publication number Priority date Publication date Assignee Title
DE9115218U1 (en) * 1991-12-07 1992-03-19 Dirler, Karin, 6082 Mörfelden-Walldorf Ignition device for motor vehicle - petrol engines
DE19747700C2 (en) * 1997-10-29 2000-06-29 Volkswagen Ag Ignition device with an ignition electrode
DE19747701C2 (en) * 1997-10-29 1999-12-23 Volkswagen Ag Plasma jet ignition for internal combustion engines
DE10048053A1 (en) * 2000-09-28 2002-06-06 Christoph Koerber Plasma jet ignition system for spark ignition engines, includes UV-triggered gas discharge tube and component controlling current flow to spark
DE10331418A1 (en) * 2003-07-10 2005-01-27 Bayerische Motoren Werke Ag Plasma jet spark plug
JP7186044B2 (en) 2018-09-26 2022-12-08 株式会社Soken Spark plug for internal combustion engine

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Publication number Priority date Publication date Assignee Title
GB215822A (en) * 1923-02-13 1924-05-13 William Peck Improvements in sparking plugs
US3842819A (en) * 1971-11-16 1974-10-22 Ass Eng Ltd Ignition devices

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GB215822A (en) * 1923-02-13 1924-05-13 William Peck Improvements in sparking plugs
US3842819A (en) * 1971-11-16 1974-10-22 Ass Eng Ltd Ignition devices

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Title
PATENT ABSTRACTS OF JAPAN vol. 7, no. 291 (M-265)(1436) 27. Dezember 1983 & JP-A-58 162 719 ( NISSAN JIDOSHA K.K. ) 27. September 1983 *

Cited By (2)

* Cited by examiner, † Cited by third party
Publication number Priority date Publication date Assignee Title
EP2088653A3 (en) * 2008-02-06 2013-05-22 NGK Spark Plug Co., Ltd. Plasma jet ignition plug
US8729782B2 (en) 2010-10-28 2014-05-20 Federal-Mogul Ignition Non-thermal plasma ignition arc suppression

Also Published As

Publication number Publication date
EP0475288B1 (en) 1995-01-04
DE59104133D1 (en) 1995-02-16
DE4028869A1 (en) 1992-03-19

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