EP2089944A1 - Sparkplug, in particular for high combustion chamber pressures - Google Patents

Sparkplug, in particular for high combustion chamber pressures

Info

Publication number
EP2089944A1
EP2089944A1 EP07787409A EP07787409A EP2089944A1 EP 2089944 A1 EP2089944 A1 EP 2089944A1 EP 07787409 A EP07787409 A EP 07787409A EP 07787409 A EP07787409 A EP 07787409A EP 2089944 A1 EP2089944 A1 EP 2089944A1
Authority
EP
European Patent Office
Prior art keywords
insulator
conductive
spark plug
sheet
housing
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
EP07787409A
Other languages
German (de)
French (fr)
Other versions
EP2089944B1 (en
Inventor
Thomas Kaiser
Paulo Ricardo
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 EP2089944A1 publication Critical patent/EP2089944A1/en
Application granted granted Critical
Publication of EP2089944B1 publication Critical patent/EP2089944B1/en
Expired - Fee Related legal-status Critical Current
Anticipated expiration legal-status Critical

Links

Classifications

    • 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
    • H01T13/20—Sparking plugs characterised by features of the electrodes or insulation
    • H01T13/36—Sparking plugs characterised by features of the electrodes or insulation characterised by the joint between insulation and body, e.g. using cement
    • 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
    • H01T13/20—Sparking plugs characterised by features of the electrodes or insulation
    • H01T13/38—Selection of materials for insulation

Definitions

  • the present invention relates to a spark plug for internal combustion engines, which is designed in particular for use in combustion chambers with high pressure.
  • Spark plugs are known from the prior art in different configurations.
  • the known spark plugs have basically proven themselves for use in internal combustion engines.
  • the pressures in the combustion chamber at the time of ignition are getting larger, since the internal combustion engines are increasingly charged and operated with high compression.
  • it may lead to the formation of sliding sparks during ignition, which in particular also into a respiratory chamber of the spark plug, which is formed between a tapered region of the insulator and a housing of the spark plug at the combustion chamber end of the spark plug.
  • Such sliding sparks lead in the homogeneous operation of the internal combustion engine to a turbulent engine run. In stratified operation of the internal combustion engine and in operating states with inhomogeneous mixture distribution, such. During low-temperature starts, sliding sparks cause frequent misfires.
  • the spark plug according to the invention with the features of claim 1 has the advantage that it prevents the formation of sliding sparks. This allows the spark plug according to the invention in particular in internal combustion engines with high Press, such as charged and / or high-compression engines used.
  • the spark plug according to the invention has a long service life and can be produced easily and inexpensively. This is inventively achieved in that on the insulator of the spark plug, a conductive sheet-like element is arranged, which is in electrical contact with the housing. As a result, it is achieved according to the invention that the
  • Insulator surface is placed on the electrical potential of the housing.
  • the housing is usually grounded.
  • Partial discharges are avoided in the housing web area and thus also electromagnetic interference pulses are suppressed.
  • the conductive, sheet-like element is preferably formed as extending completely around the insulator band.
  • an emergence of electric fields in the critical region of the respiratory space between the insulation and the housing can be reliably prevented.
  • the conductive, sheet-like element is arranged in the region of a sealing seat between the housing and the insulator. As a result, a secure contact can be achieved.
  • the spark plug comprises a sealing ring, which is arranged between the housing and the insulator, and the sealing ring is made of an electrically conductive material.
  • the conductive, sheet-like element according to the invention is arranged on a region of the insulator which is positioned at the level of the sealing ring.
  • the conductive, sheet-like element has a maximum thickness of 100 microns.
  • the conductive sheet-like member is further preferably provided with a constant thickness. This upper limit of the thickness of the element has the advantage that a simple attachment is guaranteed. It should also be noted that as the layer thickness increases, stresses in the material significantly increase, thereby deteriorating the attachment of the element.
  • the thickness of the conductive, sheet-like element is in the range of about 50 microns to about 80 microns.
  • the conductive, sheet-like element is arranged on the insulator at a region of the insulator, which is arranged in the mounted state at the level of an inner, circumferential web of the housing.
  • the conductive, sheet-like element on the insulator covers at least 70% of the surface of the insulator, which is directed to the inner web of the housing in the radial direction of the spark plug.
  • the conductive sheet-like element starting from a contact point between the insulator and the housing, covers a region of the insulator in the direction of its end surface on which the electrodes are arranged, the area provided with the conductive, planar element being a maximum of 50%, preferably 30 % of the distance between the contact point and the end face of the insulator.
  • the conductive sheet-like member covers an area of at least 70% of a portion of the insulator having a pitch of less than or equal to 0.5mm from the inner surface of the housing. This also ensures that the critical area for the emergence of sliding sparks in the working space is made field-free.
  • the conductive, sheet-like element is a conductive coating.
  • the coating is a conductive ink, which has an electrical conductivity.
  • the conductive ink includes preferably a noble metal, in particular silver and / or platinum and / or gold and / or iridium and / or rhodium, and / or tantalum and / or nickel and / or carbon or any oxidation-resistant alloy thereof.
  • the oxidation resistance is important because high temperatures and atmospheric oxygen are present in the combustion chamber.
  • a thin tape e.g. Gold leaf or other precious metal-containing film can be used.
  • Figure 1 is a schematic, partially sectioned partial view of a spark plug according to an embodiment of the invention.
  • Figure 2 is a diagram showing the probability of the occurrence of sliding sparks in
  • the spark plug 1 comprises a housing 2 having an external thread 2a, with which the spark plug 1 is attached to a component of an internal combustion engine.
  • the spark plug 1 further includes an insulator 3 with a combustion chamber side end face 3 a.
  • a center electrode 4 is arranged, which is arranged in the longitudinal direction X-X of the spark plug.
  • a ground electrode 5 is connected to the housing 2.
  • a respiratory space 6 is formed between the insulator 3 and the housing 2.
  • the respiratory space 6 is annular and tapers from the electrode-side end of the spark plug.
  • the web 2b has an annular shape and a seal 9 is arranged at a step transition between the web 2b and the inside of the housing between the housing 2 and the insulator 3.
  • a coating 7 made of a silver conductive paint is further applied at the level of the web 2b.
  • the silver conductive ink can be applied to the insulator 3, for example, by spraying or rolling.
  • the contact point 8 is an electrically conductive contact between the housing 2 and the coating 7, so that it is achieved that the outer surface of the insulator is placed in the region of the respiratory space 6 to the electrical potential of the housing.
  • electric fields can be prevented from building up between the insulator 3 and the inside of the housing 2, which could lead to a sliding spark jumping over the end face 3a of the insulator 3 into the respiratory space 6 during the ignition time.
  • the conductive coating 7 eliminates these electric fields in the region of the inner web 2 b of the housing 2.
  • FIG. 2 shows a diagram which shows a comparison of a spark plug with an insulator without a coating according to the prior art and a spark plug according to the invention with an insulator having a coating of silver conductive paint.
  • the curve of the spark plug is marked with an insulator without coating with "N” and the curve of the spark plug with an insulator with coating marked with "M”.
  • "W” indicates the probability of a sliding spark in%.
  • the spark plug according to the invention has only a minimal probability of producing a sliding spark, even at very high pressures.
  • the coating 7 is provided on the insulator 3 at a width B in the longitudinal direction XX of the spark plug starting from the contact point 8, wherein a ratio of the width B to a distance A from the contact point 8 to the end face 3 a of the insulator 3 is about 1: 4.
  • the coating 7 is formed over a surface area starting from the contact point 8 of approximately 25% of the insulator surface from the contact point 8 to the end face 3 a.
  • the coating 7 is provided completely over the entire width of the web 2b.
  • An overlap of the coating 7 in the region of the web 2b should amount to at least 70% of the web width to the area prone to the unwanted pre-discharges between the insulator 3 and the housing 2 to make field-free. It should also be noted that the coating 7 on the insulator 3 should be at most 50%, particularly preferably at most 30%, of the distance A between the contact point 8 and the end face 3a.
  • the coating used is preferably a conductive paint which comprises a noble metal or an oxidation-resistant conductive alloy, since very high temperatures often occur in the combustion chamber.
  • the present invention can be used in all known fields of use of spark plugs, but is particularly preferably used when high pressures occur in combustion chambers.

Landscapes

  • Spark Plugs (AREA)

Abstract

The present invention relates to a sparkplug with a central electrode (4) arranged within an insulator (3) and a housing (2), which surrounds at least regions of the insulator (3), characterized in that a conductive planar element (7) is arranged on the insulator (3), and electrical contact is made between said element and the housing (2).

Description

Beschreibung description
Titeltitle
Zündkerze, insbesondere für hohe BrennraumdrückeSpark plug, especially for high combustion chamber pressures
Stand der TechnikState of the art
Die vorliegende Erfindung betrifft eine Zündkerze für Brennkraftmaschinen, welche insbesondere zur Verwendung in Brennräumen mit hohem Druck ausgelegt ist.The present invention relates to a spark plug for internal combustion engines, which is designed in particular for use in combustion chambers with high pressure.
Zündkerzen sind aus dem Stand der Technik in unterschiedlichen Ausgestaltungen bekannt. Die bekannten Zündkerzen haben sich grundsätzlich zur Verwendung in Brennkraftmaschinen bewährt. Allerdings werden in jüngster Zeit die Drücke im Brennraum zum Zündzeitpunkt immer größer, da die Brennkraftmaschinen verstärkt aufgeladen werden und mit hoher Verdichtung betrieben werden. Dabei kann es insbesondere bei hohen Drücken zur Entstehung von Gleitfunken bei der Zündung kommen, welche insbesondere auch bis in einen Atmungsraum der Zündkerze, welcher zwischen einem sich verjüngenden Bereich des Isolators und einem Gehäuse der Zündkerze an dem brennraumseitigen Ende der Zündkerze gebildet ist. Derartige Gleitfunken führen im homogenen Betrieb der Brennkraftmaschine zu einem unruhigen Motorlauf. Im Schichtbetrieb der Brennkraftmaschine und bei Betriebszuständen mit inhomogener Gemischverteilung, wie z.B. bei Tieftemperaturstarts, bewirken Gleitfunken gehäuft auftretende Verbrennungsaussetzer.Spark plugs are known from the prior art in different configurations. The known spark plugs have basically proven themselves for use in internal combustion engines. However, in recent times, the pressures in the combustion chamber at the time of ignition are getting larger, since the internal combustion engines are increasingly charged and operated with high compression. In particular, at high pressures, it may lead to the formation of sliding sparks during ignition, which in particular also into a respiratory chamber of the spark plug, which is formed between a tapered region of the insulator and a housing of the spark plug at the combustion chamber end of the spark plug. Such sliding sparks lead in the homogeneous operation of the internal combustion engine to a turbulent engine run. In stratified operation of the internal combustion engine and in operating states with inhomogeneous mixture distribution, such. During low-temperature starts, sliding sparks cause frequent misfires.
In der DE 196 50 724 B4 wurde zur Reduzierung von Gleitfunken vorgeschlagen, einen Elektrodenabstand zwischen der Mittelelektrode und der Masseelektrode derart vorzusehen, dass dieser Elektrodenabstand kleiner als ein Abstand der Mittelelektrode zum Gehäuse ist. Die hierbei vorgeschlagenen geometrischen Anordnungen der Elektroden können jedoch häufig aufgrund von bauraumbedingen Vorgaben nicht eingehalten werden.In DE 196 50 724 B4 has been proposed for the reduction of sliding sparks, to provide an electrode spacing between the center electrode and the ground electrode such that this electrode spacing is smaller than a distance of the center electrode to the housing. However, the geometric arrangements of the electrodes proposed here can often not be complied with due to design constraints.
Vorteile der ErfindungAdvantages of the invention
Die erfindungsgemäße Zündkerze mit den Merkmalen des Patentanspruchs 1 weist demgegenüber den Vorteil auf, dass sie die Entstehung von Gleitfunken verhindert. Dadurch kann die erfindungsgemäße Zündkerze insbesondere in Brennkraftmaschinen mit hohen Drücken, wie z.B. aufgeladenen und/oder hochverdichteten Motoren, verwendet werden. Die erfindungsgemäße Zündkerze weist dabei eine hohe Lebensdauer und kann einfach und kostengünstig hergestellt werden. Dies wird erfindungsgemäß dadurch erreicht, dass auf dem Isolator der Zündkerze ein leitfähiges flächenartiges Element angeordnet ist, welche mit dem Gehäuse elektrisch in Kontakt steht. Dadurch wird erfindungsgemäß erreicht, dass dieThe spark plug according to the invention with the features of claim 1 has the advantage that it prevents the formation of sliding sparks. This allows the spark plug according to the invention in particular in internal combustion engines with high Press, such as charged and / or high-compression engines used. The spark plug according to the invention has a long service life and can be produced easily and inexpensively. This is inventively achieved in that on the insulator of the spark plug, a conductive sheet-like element is arranged, which is in electrical contact with the housing. As a result, it is achieved according to the invention that the
Isolatoroberfläche auf das elektrische Potential des Gehäuses gelegt wird. Das Gehäuse ist dabei üblicherweise geerdet. Durch diese relativ einfache erfindungsgemäße Maßnahme können elektrische Felder, welche im Atmungsraum zwischen der sich verjüngenden Isolation und dem Gehäuse bei konventionellen Zündkerzen vorhanden sind, eliminiert werden. Dadurch kann auch bei hohen Drücken die Erzeugung von Gleitfunken verhindert werden. Ferner könnenInsulator surface is placed on the electrical potential of the housing. The housing is usually grounded. By virtue of this relatively simple measure according to the invention, electric fields which are present in the respiratory space between the tapered insulation and the housing in conventional spark plugs can be eliminated. As a result, the generation of sliding sparks can be prevented even at high pressures. Furthermore, can
Teilentladungen im Gehäusestegbereich vermieden werden und somit auch elektromagnetische Störpulse unterdrückt werden.Partial discharges are avoided in the housing web area and thus also electromagnetic interference pulses are suppressed.
Die Unteransprüche zeigen bevorzugte Weiterbildungen der Erfindung.The dependent claims show preferred developments of the invention.
Das leitfähige, flächenartige Element ist vorzugsweise als vollständig um den Isolator verlaufendes Band ausgebildet. Dadurch kann sicher eine Entstehung elektrischer Felder im kritischen Bereich des Atmungsraums zwischen der Isolation und dem Gehäuse verhindert werden. Es sei angemerkt, dass es alternativ auch möglich ist, mehrere nur teilweise umlaufende Bereiche mit dem erfindungsgemäßen leitfähigen, flächenartigen Element zu versehen, wobei benachbarte Flächenelemente nur in geringem Umfang voneinander beabstandet sind. Hierbei muss jedoch eine elektrische Verbindung jedes Elements zum Gehäuse vorhanden sein.The conductive, sheet-like element is preferably formed as extending completely around the insulator band. As a result, an emergence of electric fields in the critical region of the respiratory space between the insulation and the housing can be reliably prevented. It should be noted that it is alternatively also possible to provide a plurality of only partially circumferential areas with the conductive, sheet-like element according to the invention, wherein adjacent surface elements are only slightly spaced from each other. However, there must be an electrical connection of each element to the housing.
Besonders bevorzugt ist das leitfähige, flächenartige Element im Bereich eines Dichtsitzes zwischen dem Gehäuse und dem Isolator angeordnet. Dadurch kann eine sichere Kontaktierung erreicht werden.Particularly preferably, the conductive, sheet-like element is arranged in the region of a sealing seat between the housing and the insulator. As a result, a secure contact can be achieved.
Weiter bevorzugt umfasst die Zündkerze einen Dichtring, welcher zwischen dem Gehäuse und dem Isolator angeordnet ist, und der Dichtring ist aus einem elektrisch leitenden Material hergestellt. Das erfindungsgemäße leitfähige, flächenartige Element ist dabei an einem Bereich des Isolators angeordnet, welcher auf Höhe des Dichtrings positioniert ist.More preferably, the spark plug comprises a sealing ring, which is arranged between the housing and the insulator, and the sealing ring is made of an electrically conductive material. The conductive, sheet-like element according to the invention is arranged on a region of the insulator which is positioned at the level of the sealing ring.
Gemäß einer weiteren bevorzugten Ausgestaltung der vorliegenden Erfindung weist das leitfähige, flächenartige Element eine Dicke von maximal 100 μm auf. Das leitfähige, flächenartige Element ist weiter bevorzugt mit einer konstanten Dicke vorgesehen. Diese Obergrenze der Dicke des Elements weist den Vorteil auf, dass eine einfache Befestigung gewährleistet ist. Es sei ferner angemerkt, dass mit einer größer werdenden Schichtdicke Spannungen im Material erheblich ansteigen, wodurch sich die Befestigung des Elements verschlechtert. Besonders bevorzugt liegt die Dicke des leitfähigen, flächenartigen Elements im Bereich von ca. 50 μm bis ca. 80 μm.According to a further preferred embodiment of the present invention, the conductive, sheet-like element has a maximum thickness of 100 microns. The conductive sheet-like member is further preferably provided with a constant thickness. This upper limit of the thickness of the element has the advantage that a simple attachment is guaranteed. It should also be noted that as the layer thickness increases, stresses in the material significantly increase, thereby deteriorating the attachment of the element. Particularly preferably, the thickness of the conductive, sheet-like element is in the range of about 50 microns to about 80 microns.
Weiter bevorzugt ist das leitfähige, flächenartige Element am Isolator an einem Bereich des Isolators angeordnet, welcher im montierten Zustand auf Höhe eines inneren, umlaufenden Stegs des Gehäuses angeordnet ist. Vorzugsweise überdeckt das leitfähige, flächenartige Element am Isolator dabei wenigstens 70% der Fläche des Isolators, welche zum inneren Steg des Gehäuses in Radialrichtung der Zündkerze gerichtet ist. Durch diese Maßnahme wird sichergestellt, dass der für die Bildung von elektrischen Feldern anfällige Raum zwischen dem inneren Steg des Gehäuse und dem Isolator zumindest zu 70% mit dem elektrisch leitenden Element überdeckt ist. Dadurch kann dieser für Vorentladungen anfällige Bereich feldfrei gemacht werden, so dass die Neigung zur Entstehung von Gleitfunken reduziert ist. Es sei ferner angemerkt, dass das leitfähige, flächenartige Element am Isolator nicht zu weit in Richtung der Elektroden reichen darf, da sich sonst eine Nebenanschlussanfälligkeit der Zündkerze wesentlich erhöht.More preferably, the conductive, sheet-like element is arranged on the insulator at a region of the insulator, which is arranged in the mounted state at the level of an inner, circumferential web of the housing. Preferably, the conductive, sheet-like element on the insulator covers at least 70% of the surface of the insulator, which is directed to the inner web of the housing in the radial direction of the spark plug. By this measure, it is ensured that the space prone to the formation of electric fields between the inner web of the housing and the insulator is at least 70% covered with the electrically conductive element. As a result, this area, which is susceptible to preliminary discharges, can be made field-free, so that the tendency for the occurrence of sliding sparks is reduced. It should also be noted that the conductive, sheet-like element on the insulator may not extend too far in the direction of the electrodes, since otherwise a connection resistance of the spark plug substantially increases.
Vorzugsweise bedeckt das leitfähige, flächenartige Element, ausgehend von einer Kontaktstelle zwischen Isolator und Gehäuse, einen Bereich des Isolators in Richtung von dessen Stirnfläche, an welcher die Elektroden angeordnet sind, wobei der mit dem leitfähigen, flächenartigen Element versehene Bereich maximal 50%, vorzugsweise 30% des Abstandes zwischen der Kontaktstelle und der Stirnfläche des Isolators ist.Preferably, the conductive sheet-like element, starting from a contact point between the insulator and the housing, covers a region of the insulator in the direction of its end surface on which the electrodes are arranged, the area provided with the conductive, planar element being a maximum of 50%, preferably 30 % of the distance between the contact point and the end face of the insulator.
Vorzugsweise bedeckt das leitfähige, flächenartige Element eine Fläche von mindestens 70% eines Bereichs des Isolators, welcher zur Innenfläche des Gehäuses einen Abstand von kleiner gleich 0,5 mm aufweist. Dies stellt ebenfalls sicher, dass der für die Entstehung von Gleitfunken in den Arbeitsraum kritische Bereich feldfrei gemacht wird.Preferably, the conductive sheet-like member covers an area of at least 70% of a portion of the insulator having a pitch of less than or equal to 0.5mm from the inner surface of the housing. This also ensures that the critical area for the emergence of sliding sparks in the working space is made field-free.
Besonders bevorzugt ist das leitfähige, flächenartige Element eine leitfähige Beschichtung.Particularly preferably, the conductive, sheet-like element is a conductive coating.
Diese ist einfach und kostengünstig aufbringbar und weist nur eine geringe Dichte auf.This is easy and inexpensive to apply and has only a low density.
Besonders bevorzugt ist die Beschichtung ein Leitlack, welcher eine elektrische Leitfähigkeit aufweist. Dies hat insbesondere den Vorteil, dass die Beschichtung besonders einfach und kostengünstig aufgebracht werden kann. Dabei ist es auch nicht notwendig, dass bisherige Montageverfahren von Zündkerzen geändert werden müssen. Der Leitlack umfasst vorzugsweise ein Edelmetall, insbesondere Silber und/oder Platin und/oder Gold und/oder Iridium und/oder Rhodium, und/oder Tantal und/oder Nickel und/oder Kohlenstoff oder eine beliebige oxidationsbeständige Legierung hiervon. Die Oxidationsbeständigkeit ist wichtig, da im Brennraum hohe Temperaturen und Luftsauerstoff vorhanden sind.Particularly preferably, the coating is a conductive ink, which has an electrical conductivity. This has the particular advantage that the coating can be applied in a particularly simple and cost-effective manner. It is also not necessary that previous assembly process of spark plugs must be changed. The conductive ink includes preferably a noble metal, in particular silver and / or platinum and / or gold and / or iridium and / or rhodium, and / or tantalum and / or nickel and / or carbon or any oxidation-resistant alloy thereof. The oxidation resistance is important because high temperatures and atmospheric oxygen are present in the combustion chamber.
Als leitfähiges, flächenartiges Element kann auch ein dünnes Band bzw. eine dünne Folie, z.B. Blattgold oder eine andere Edelmetall-haltige Folie, verwendet werden.As a conductive sheet-like member, a thin tape, e.g. Gold leaf or other precious metal-containing film can be used.
Zeichnungdrawing
Nachfolgend wird ein bevorzugtes Ausführungsbeispiel der Erfindung unter Bezugnahme auf die begleitende Zeichnung beschrieben. In der Zeichnung ist:Hereinafter, a preferred embodiment of the invention will be described with reference to the accompanying drawings. In the drawing is:
Figur 1 eine schematische, teilweise geschnittene Teilansicht einer Zündkerze gemäß einem Ausführungsbeispiel der Erfindung undFigure 1 is a schematic, partially sectioned partial view of a spark plug according to an embodiment of the invention and
Figur 2 ein Diagramm, welches die Wahrscheinlichkeit des Entstehens von Gleitfunken inFigure 2 is a diagram showing the probability of the occurrence of sliding sparks in
Abhängigkeit vom Druck im Brennraum für eine erfindungsgemäße Zündkerze sowie eine Zündkerze des Standes der Technik zeigt.Dependence of the pressure in the combustion chamber for a spark plug according to the invention and a spark plug of the prior art shows.
Bevorzugte Ausführungsform der ErfindungPreferred embodiment of the invention
Nachfolgend wird unter Bezugnahme auf die Figuren 1 und 2 eine Zündkerze 1 gemäß einem Ausführungsbeispiel der Erfindung im Detail beschrieben.Hereinafter, a spark plug 1 according to an embodiment of the invention will be described in detail with reference to Figures 1 and 2.
Wie in Figur 1 gezeigt, umfasst die Zündkerze 1 ein Gehäuse 2, welches ein Außengewinde 2a aufweist, mit welchem die Zündkerze 1 an einem Bauteil einer Brennkraftmaschine befestigt wird. Die Zündkerze 1 umfasst ferner einen Isolator 3 mit einer brennraumseitigen Stirnfläche 3 a. Im Inneren des Isolators 3 ist eine Mittelelektrode 4 angeordnet, welche in Längsrichtung X- X der Zündkerze angeordnet ist. Eine Masseelektrode 5 ist mit dem Gehäuse 2 verbunden.As shown in Figure 1, the spark plug 1 comprises a housing 2 having an external thread 2a, with which the spark plug 1 is attached to a component of an internal combustion engine. The spark plug 1 further includes an insulator 3 with a combustion chamber side end face 3 a. In the interior of the insulator 3, a center electrode 4 is arranged, which is arranged in the longitudinal direction X-X of the spark plug. A ground electrode 5 is connected to the housing 2.
Wie aus Figur 1 ersichtlich ist, ist zwischen dem Isolator 3 und dem Gehäuse 2 ein Atmungsraum 6 ausgebildet. Der Atmungsraum 6 ist ringförmig vorgesehen und verjüngt sich ausgehend vom Elektroden-seitigen Ende der Zündkerze. An der Innenseite des Gehäuses 2 ist ferner ein innerer umlaufender Steg 2b ausgebildet. Der Steg 2b weist eine ringförmige Gestalt auf und eine Dichtung 9 ist an einem Stufenübergang zwischen dem Steg 2b und der Innenseite des Gehäuses zwischen dem Gehäuse 2 und dem Isolator 3 angeordnet.As can be seen from FIG. 1, a respiratory space 6 is formed between the insulator 3 and the housing 2. The respiratory space 6 is annular and tapers from the electrode-side end of the spark plug. On the inside of the housing 2, an inner circumferential web 2b is further formed. The web 2b has an annular shape and a seal 9 is arranged at a step transition between the web 2b and the inside of the housing between the housing 2 and the insulator 3.
Am Isolator 3 ist ferner auf der Höhe des Stegs 2b eine Beschichtung 7 aus einem Silberleitlack aufgebracht. Der Silberleitlack kann beispielsweise durch Aufsprühen oder Aufwalzen auf den Isolator 3 aufgebracht werden. Im Bereich der Stufe am Steg 2b liegt eine ringförmige Kontaktstelle 8 zwischen dem Gehäuse 2 und der Beschichtung 7. Die Kontaktstelle 8 stellt einen elektrisch leitenden Kontakt zwischen dem Gehäuse 2 und der Beschichtung 7 dar, so dass erreicht wird, dass die Außenfläche des Isolators 3 im Bereich des Atmungsraums 6 auf das elektrische Potential des Gehäuses gelegt wird. Dadurch kann verhindert werden, dass sich zwischen dem Isolator 3 und der Innenseite des Gehäuses 2 elektrische Felder aufbauen, welche dazu führen könnten, dass während des Zündzeitpunkts ein Gleitfunken über die Stirnfläche 3 a des Isolators 3 in den Atmungsraum 6 springt. Die leitfähige Beschichtung 7 eliminiert diese elektrischen Felder im Bereich des inneren Stegs 2b des Gehäuses 2. Somit kann erfmdungsge- maß insbesondere bei hohen Drücken das Entstehen eines Gleitfunkens verhindert werden.On the insulator 3, a coating 7 made of a silver conductive paint is further applied at the level of the web 2b. The silver conductive ink can be applied to the insulator 3, for example, by spraying or rolling. In the region of the step on the web 2b is an annular contact point 8 between the housing 2 and the coating 7. The contact point 8 is an electrically conductive contact between the housing 2 and the coating 7, so that it is achieved that the outer surface of the insulator is placed in the region of the respiratory space 6 to the electrical potential of the housing. As a result, electric fields can be prevented from building up between the insulator 3 and the inside of the housing 2, which could lead to a sliding spark jumping over the end face 3a of the insulator 3 into the respiratory space 6 during the ignition time. The conductive coating 7 eliminates these electric fields in the region of the inner web 2 b of the housing 2. Thus, it is possible, according to the invention, to prevent the occurrence of a sliding spark, especially at high pressures.
Figur 2 zeigt hierzu ein Diagramm, welches einen Vergleich einer Zündkerze mit einem Isolator ohne Beschichtung gemäß dem Stand der Technik sowie eine erfindungsgemäße Zündkerze mit einem eine Beschichtung aus Silberleitlack aufweisenden Isolator zeigt. In Figur 2 ist die Kurve der Zündkerze mit einem Isolator ohne Beschichtung mit "N" gekennzeichnet und die Kurve der Zündkerze mit einem Isolator mit Beschichtung mit "M" gekennzeichnet. "W" bezeichnet die Wahrscheinlichkeit für einen Gleitfunken in %. Wie aus dem Diagramm von Figur 2 ersichtlich ist, weist die erfindungsgemäße Zündkerze auch bei sehr hohen Drücken nur eine minimale Wahrscheinlichkeit für die Entstehung eines Gleitfunkens auf. Im Unterschied dazu ist bei der Zündkerze nach dem Stand der Technik ein signifikanter Anstieg der Wahrscheinlichkeit für dasFIG. 2 shows a diagram which shows a comparison of a spark plug with an insulator without a coating according to the prior art and a spark plug according to the invention with an insulator having a coating of silver conductive paint. In Figure 2, the curve of the spark plug is marked with an insulator without coating with "N" and the curve of the spark plug with an insulator with coating marked with "M". "W" indicates the probability of a sliding spark in%. As can be seen from the diagram of FIG. 2, the spark plug according to the invention has only a minimal probability of producing a sliding spark, even at very high pressures. In contrast, in the prior art spark plug, there is a significant increase in the likelihood of this
Auftreten eines Gleitfunkens ab einem Druck von ca. 7 x 105 Pascal ersichtlich.Occurs on a gliding spark from a pressure of about 7 x 10 5 Pascal.
Aus Figur 1 ist ferner ersichtlich, dass die Beschichtung 7 auf dem Isolator 3 auf einer Breite B in Längsrichtung X-X der Zündkerze ausgehend von der Kontaktstelle 8 vorgesehen ist, wobei ein Verhältnis der Breite B zu einem Abstand A von der Kontaktstelle 8 zu der Stirnfläche 3 a des Isolators 3 ungefähr 1 :4 beträgt. Mit anderen Worten ist die Beschichtung 7 über einen Flächenbereich ausgehend von der Kontaktstelle 8 von ca. 25% der Isolatoroberfläche von der Kontaktstelle 8 bis zur Stirnfläche 3 a gebildet. Wie ferner aus Figur 1 ersichtlich ist, ist dabei die Beschichtung 7 vollständig über die gesamte Breite des Stegs 2b vorgesehen. Eine Überdeckung der Beschichtung 7 im Bereich des Stegs 2b sollte dabei mindestens 70% der Stegbreite betragen, um den für die unerwünschten Vorentladungen anfälligen Bereich zwischen dem Isolator 3 und dem Gehäuse 2 feldfrei zu machen. Hierbei sei ferner angemerkt, dass die Beschichtung 7 auf dem Isolator 3 höchstens 50%, besonders bevorzugt höchstens 30%, des Abstands A zwischen der Kontaktstelle 8 und der Stirnfläche 3a betragen sollte.It is further apparent from FIG. 1 that the coating 7 is provided on the insulator 3 at a width B in the longitudinal direction XX of the spark plug starting from the contact point 8, wherein a ratio of the width B to a distance A from the contact point 8 to the end face 3 a of the insulator 3 is about 1: 4. In other words, the coating 7 is formed over a surface area starting from the contact point 8 of approximately 25% of the insulator surface from the contact point 8 to the end face 3 a. As can also be seen from FIG. 1, the coating 7 is provided completely over the entire width of the web 2b. An overlap of the coating 7 in the region of the web 2b should amount to at least 70% of the web width to the area prone to the unwanted pre-discharges between the insulator 3 and the housing 2 to make field-free. It should also be noted that the coating 7 on the insulator 3 should be at most 50%, particularly preferably at most 30%, of the distance A between the contact point 8 and the end face 3a.
Als Beschichtung wird vorzugsweise ein Leitlack, welcher ein Edelmetall oder eine oxidationsbeständige leitende Legierung aufweist, verwendet, da im Brennraum oft sehr hohe Temperaturen auftreten.The coating used is preferably a conductive paint which comprises a noble metal or an oxidation-resistant conductive alloy, since very high temperatures often occur in the combustion chamber.
Die vorliegende Erfindung kann bei allen bekannten Einsatzgebieten von Zündkerzen verwendet werden, besonders bevorzugt wird sie jedoch bei Auftreten hoher Drücke in Brennräumen verwendet. The present invention can be used in all known fields of use of spark plugs, but is particularly preferably used when high pressures occur in combustion chambers.

Claims

Ansprüche claims
1. Zündkerze mit einer innerhalb eines Isolators (3) angeordneten Mittelelektrode (4) und einem Gehäuse (2), welches den Isolator (3) zumindest bereichsweise umgibt, dadurch gekennzeichnet, dass am Isolator (3) ein leitfähiges flächenartiges Element (7) angeordnet ist, welches mit dem Gehäuse (2) elektrisch kontaktiert ist.1. spark plug with a within an insulator (3) arranged center electrode (4) and a housing (2) which surrounds the insulator (3) at least partially, characterized in that the insulator (3) a conductive sheet-like element (7) is, which is electrically contacted with the housing (2).
2. Zündkerze nach Anspruch 1, dadurch gekennzeichnet, dass das leitfähige, flächenartige Element (7) als vollständig um den Isolator (3) umlaufender Bereich ausgebildet ist.2. Spark plug according to claim 1, characterized in that the conductive, sheet-like element (7) as completely around the insulator (3) circumferential region is formed.
3. Zündkerze nach einem der vorhergehenden Ansprüche, dadurch gekennzeichnet, dass das leitfähige, flächenartige Element (7) im Bereich eines Dichtsitzes zwischen dem Gehäuse3. Spark plug according to one of the preceding claims, characterized in that the conductive, sheet-like element (7) in the region of a sealing seat between the housing
(2) und dem Isolator (3) angeordnet ist.(2) and the insulator (3) is arranged.
4. Zündkerze nach einem der vorhergehenden Ansprüche, ferner umfassend eine Dichtung (9), welche zwischen dem Gehäuse (2) und dem Isolator (3) angeordnet ist, wobei die Dichtung (9) aus einem elektrisch leitenden Material hergestellt ist und das Gehäuse (2) und das leitfähige, flächenartige Element (7) kontaktiert.A spark plug according to any one of the preceding claims, further comprising a seal (9) disposed between the housing (2) and the insulator (3), the seal (9) being made of an electrically conductive material and the housing ( 2) and the conductive, sheet-like element (7) contacted.
5. Zündkerze nach einem der vorhergehenden Ansprüche, dadurch gekennzeichnet, dass das leitfähige, flächenartige Element (7) eine Dicke von maximal 100 μm, vorzugsweise ca. 50 μm bis ca. 80 μm, aufweist.5. Spark plug according to one of the preceding claims, characterized in that the conductive, sheet-like element (7) has a thickness of not more than 100 microns, preferably about 50 microns to about 80 microns.
6. Zündkerze nach einem der vorhergehenden Ansprüche, dadurch gekennzeichnet, dass das leitfähige, flächenartige Element (7) am Isolator (3) auf Höhe eines inneren umlaufenden Steges (2b) des Gehäuses (2) angeordnet ist.6. Spark plug according to one of the preceding claims, characterized in that the conductive, sheet-like element (7) on the insulator (3) at the level of an inner circumferential web (2b) of the housing (2) is arranged.
7. Zündkerze nach Anspruch 6, dadurch gekennzeichnet, dass das leitfähige, flächenartige Element (7) am Isolator (3) wenigstens 70% einer Fläche des Isolators bedeckt, welche zum Steg (2b) des Gehäuses (2) gerichtet ist.7. Spark plug according to claim 6, characterized in that the conductive, sheet-like element (7) on the insulator (3) covers at least 70% of a surface of the insulator, which is directed to the web (2b) of the housing (2).
8. Zündkerze nach einem der vorhergehenden Ansprüche, dadurch gekennzeichnet, dass das leitfähige, flächenartige Element (7), ausgehend von einer Kontaktstelle (8) zwischen dem leitfähigen, flächenartigen Element (7) und dem Gehäuse (2), einen Bereich des Isolators in dessen Längsrichtung (X-X) bedeckt, welcher maximal 50%, vorzugsweise ca. 30% eines Abstands (A) zwischen der Kontaktstelle (8) und einer Stirnfläche (3a) des Isolators (3) ist.8. Spark plug according to one of the preceding claims, characterized in that the conductive, sheet-like element (7), starting from a contact point (8) between the conductive, sheet-like element (7) and the housing (2), a portion of the insulator in the longitudinal direction (XX) covered, which a maximum of 50%, preferably about 30% of a distance (A) between the contact point (8) and an end face (3a) of the insulator (3).
9. Zündkerze nach einem der vorhergehenden Ansprüche, dadurch gekennzeichnet, dass das leitfähige, flächenartige Element (7) an mindestens 70% eines Bereichs des Isolators (3) gebildet ist, welcher zur Innenfläche des Gehäuses (2) einen Abstand von kleiner oder gleich 0,5 mm aufweist.9. Spark plug according to one of the preceding claims, characterized in that the conductive, sheet-like element (7) is formed on at least 70% of a portion of the insulator (3), which to the inner surface of the housing (2) a distance of less than or equal to 0th , 5 mm.
10. Zündkerze nach einem der vorhergehenden Ansprüche, dadurch gekennzeichnet, dass das leitfähige, flächenartige Element eine Beschichtung, insbesondere ein Leitlack ist.10. Spark plug according to one of the preceding claims, characterized in that the conductive, sheet-like element is a coating, in particular a conductive ink.
11. Zündkerze nach Anspruch 10, dadurch gekennzeichnet, dass die Beschichtung ein Edelmetall, insbesondere Silber und/oder Platin und/oder Gold und/oder Iridium und/oder Rhodium, und/oder Tantal und/oder Nickel und/oder Kohlenstoff oder eine beliebige oxidationsbeständige Legierung umfasst.11. Spark plug according to claim 10, characterized in that the coating is a precious metal, in particular silver and / or platinum and / or gold and / or iridium and / or rhodium, and / or tantalum and / or nickel and / or carbon or any oxidation resistant alloy.
12. Zündkerze nach einem der Ansprüche 1 bis 9, dadurch gekennzeichnet, dass das leitfähige, flächenartige Element (7) Blattgold oder eine andere Edelmetall-haltige Folie ist. 12. Spark plug according to one of claims 1 to 9, characterized in that the conductive, sheet-like element (7) is gold leaf or another noble metal-containing film.
EP07787409A 2006-07-19 2007-07-12 Sparkplug, in particular for high combustion chamber pressures Expired - Fee Related EP2089944B1 (en)

Applications Claiming Priority (2)

Application Number Priority Date Filing Date Title
DE102006033480A DE102006033480A1 (en) 2006-07-19 2006-07-19 Spark plug, especially for high combustion chamber pressures
PCT/EP2007/057138 WO2008009610A1 (en) 2006-07-19 2007-07-12 Sparkplug, in particular for high combustion chamber pressures

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EP2089944A1 true EP2089944A1 (en) 2009-08-19
EP2089944B1 EP2089944B1 (en) 2010-12-01

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EP (1) EP2089944B1 (en)
JP (1) JP2009544129A (en)
CN (1) CN101490917A (en)
BR (1) BRPI0713050A2 (en)
DE (2) DE102006033480A1 (en)
ES (1) ES2356019T3 (en)
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US11209181B2 (en) * 2016-07-27 2021-12-28 Johnson Controls Technology Company Heating, ventilating, and air conditioning system override systems and methods
EP3545187A4 (en) 2016-11-22 2020-07-22 Ic Llc Spark plug combustion ionization sensor
JP2019110114A (en) * 2017-12-19 2019-07-04 株式会社デンソー Spark plug electrode and spark plug
JP6741717B2 (en) * 2018-04-10 2020-08-19 日本特殊陶業株式会社 Spark plug

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US20100019643A1 (en) 2010-01-28
JP2009544129A (en) 2009-12-10
ES2356019T3 (en) 2011-04-04
EP2089944B1 (en) 2010-12-01
DE102006033480A1 (en) 2008-01-24
CN101490917A (en) 2009-07-22
DE502007005876D1 (en) 2011-01-13
RU2009105396A (en) 2010-08-27
BRPI0713050A2 (en) 2012-04-17
RU2426208C2 (en) 2011-08-10
WO2008009610A1 (en) 2008-01-24

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