EP1526618A1 - Surface discharge spark plug with a directed spark - Google Patents

Surface discharge spark plug with a directed spark Download PDF

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Publication number
EP1526618A1
EP1526618A1 EP04300674A EP04300674A EP1526618A1 EP 1526618 A1 EP1526618 A1 EP 1526618A1 EP 04300674 A EP04300674 A EP 04300674A EP 04300674 A EP04300674 A EP 04300674A EP 1526618 A1 EP1526618 A1 EP 1526618A1
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EP
European Patent Office
Prior art keywords
electrode
sleeve
spark plug
spark
lug
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.)
Withdrawn
Application number
EP04300674A
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German (de)
French (fr)
Inventor
Jean Pierre Rivère
André LE NEZET
André AGNERAY
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Renault SAS
Original Assignee
Renault SAS
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Publication date
Application filed by Renault SAS filed Critical Renault SAS
Publication of EP1526618A1 publication Critical patent/EP1526618A1/en
Withdrawn legal-status Critical Current

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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
    • H01T13/52—Sparking plugs characterised by a discharge along a surface

Definitions

  • the invention relates to a spark plug for a cylinder head internal combustion engine, intended in particular to equip a motor vehicle. It also relates to a breech provided of such a candle.
  • the invention more particularly relates to a candle effect of surface, that is to say using the effects of amplification of the field in the vicinity of an insulating surface.
  • Document FR-2,816,119 describes a surface effect candle to direct the spark radially relative to the axis of the candle which prevents the candle from obscuring part of the room with spark.
  • FIG. 1 A model of surface candle described in this document is shown in Figure 1.
  • the candle is shaped to present a symmetry of revolution around its longitudinal axis. She understands a cylindrical electrode 1 electrically connected to ground, which serves as metal base. This base surrounds a high voltage electrode 2 of cylindrical shape arranged in central position.
  • the central electrode 2 is isolated from the base 1 via an insulating sleeve 3 of substantially cylindrical shape.
  • the lower end of the sleeve 3 has a circular flange shape 4 of greater diameter than rest of the sleeve.
  • the flange 4 cooperates on one of its sides with a counter electrode 5 in the form of a washer, which can be embedded in the sleeve, its opposite side having a surface 6 facing the combustion chamber.
  • the extreme part of the central electrode 2 has a radially flared shape 7 which crowns the sleeve 3.
  • the electrostatic field in the vicinity of surface 6 is then amplified by the counter electrode 5 connected to the ground electrode.
  • This candle is called radial spark surface candle in the as the spark is created on the surface 6 of the insulation, according to a direction substantially perpendicular to the axis of the candle.
  • flange-shaped part 4 of such a candle must have a low thickness to allow a good amplification of the field electrostatic on the surface of the insulation and a breakdown voltage low. This small thickness weakens it, which requires assembly accurate and low tolerance of machining parts to avoid the application of mechanical stresses on the collar.
  • the aim of the invention is to overcome these disadvantages by proposing a surface effect candle having a structure for directing spark in at least one predetermined direction while having better mechanical strength of the insulation.
  • the candle according to the invention may furthermore be manufactured at low cost with higher tolerances.
  • the candle according to the invention is particularly well adapted to an integrated use in the cylinder head, without however limit.
  • a first object of the invention relates to a candle ignition system for combustion engine cylinder head internal, having a central electrode surrounded by a sleeve insulation and a ground electrode surrounding the sleeve, said central electrode and said sleeve extending in one direction D, said sleeve ending on the side intended to be directed towards the cylinder head by a substantially flat end face along which a spark can propagate and which extends in a plane P crossed by the direction D, said candle being characterized in that the end of the central electrode protrudes from said end face of sleeve and is provided with at least one lug, each lug extending in a predetermined distinct direction E substantially parallel to the plane P, and in that it comprises at least one counter-electrode of elongate shape inserted in the insulating sleeve and connected to the ground, and one end of which is located substantially in line with a pin of the central electrode, so as to generate sufficient amplification of the electric field at the end of said pin to make
  • said at least one lug is in contact with said end face of the sleeve to reduce tension bursting of the candle.
  • the central electrode is connected to a terminal of positive polarity, so that's the ground electrode and not the insulator or the central electrode, which will wear out.
  • This choice of polarity allows also significantly reduce the breakdown voltage.
  • the electrode mass with a large volume compared to these, its wear will not affect the operation of the candle in the long run.
  • said at least one counter-electrode is substantially bar-shaped or wire-shaped and / or substantially parallel to a lug. This configuration makes it easier to insertion into the sleeve of the candle while further reducing the stresses exerted by the counter-electrode on the sleeve surrounding.
  • the portion of the sleeve bearing said face end is of asymmetrical shape and / or has a section of smaller dimensions relative to the rest of the sleeve. It is so possible to reduce the size of the candle, which allows the lodge more easily in cylinder heads with low volumes free.
  • said at least one lug has a shape elongated tapered towards its end. Such a form allows create a peak effect that promotes spark formation at the end ergot and limiting the wear of the latter.
  • the candle further comprises a metal base, said counter-electrode being shaped into the material which constitutes the pellet, and said at least one counterelectrode being in contact with, or partially embedded in, said material.
  • the counter-electrode is directly conformed in the material constituting the breech of the internal combustion engine, and said at least one counter-electrode being in contact with, or partially embedded in, said material.
  • Another object of the invention relates to a cylinder head for combustion of a motor vehicle, comprising at least one candle according to the invention, the geometry and / or the dimensions of the section of said end face of said at least one candle being selected in function of number and location of air injection lines and / or fuel present in the cylinder head.
  • the cylinder head comprises at minus one spark plug according to the invention, and each spark plug is oriented so that the direction (E) of at least one lug is directed to the air / fuel mixture, so that the spark spreads following the direction (E).
  • a candle 10 according to the invention is shown in FIGS. 3. It comprises a central electrode 11, on which will be applied a high voltage, surrounded by an insulating sleeve 12 consisting of a material whose dielectric coefficient is greater than one, for example ceramic.
  • the electrode 11 and the sleeve 12 extend in a same privileged direction D.
  • the sleeve 12 presents a symmetry of revolution whose axis is confused with the direction D.
  • the sleeve has an end face 13 substantially flat, along which the spark can spread.
  • This end face 13 extends in a plane P crossed by the direction D.
  • This plane P is perpendicular to the plane of the sheet of Figures 2 and 3.
  • the sleeve 12 presents an asymmetrically shaped portion 14.
  • This asymmetrical portion is example obtained by making indentations 15 in the walls side of the candle.
  • two indentations 15 are made, the section of the asymmetric portion 14 and the end face 13 having then substantially an acute triangle shape, the small side of the triangle being rounded ( Figures 5 to 7).
  • the section then presents a surface more small as the rest of the sleeve.
  • Such a reduction in the section of the sleeve has the advantage of reducing the bulk of the candle and to facilitate its insertion in a breech.
  • the central electrode 11 has a cylindrical rod shape whose lower end has a lug 16 which protrudes from the face end 13 of the sleeve ( Figures 2 to 4).
  • This lug 16 extends into a direction E secant direction D. It has a tapered shape towards its free end so as to limit its wear.
  • the central electrode 11 is inserted into the sleeve, for example during of its manufacture, so that the lug 16 is pressed against the face end 13 of the sleeve and thus extends substantially in the same plan as this one. In the example, it is directed to the acute angle of the end face 13 in the form of a triangle ( Figures 5 to 7).
  • the insulating sleeve 12 Near its end face 13, the insulating sleeve 12 has a counter-electrode 17, one end of which is located substantially perpendicular to the end of the lug 16, and the other end is connected to a ground electrode.
  • the counter-electrode 17 extends over the entire periphery of the sleeve, contrary, it suffices that it occupies only a small volume of the sleeve, provided that its end is substantially in line with the end of ergot.
  • the counter-electrode 17 has an elongated shape of small dimensions relative to the section of the sleeve. It is for example symmetrical, in the form of a cylindrical bar or wire of small diameter extending substantially parallel to the lug 16 at a distance d from the latter.
  • the dimensions of the counter-electrode are chosen according to the size and in order to reduce the mechanical stresses and to improve the stability of the spark. Its diameter can vary from a few microns to a few millimeters.
  • the distance d is not too high in order to limit the breakdown voltage, for example of the order of 1.5 to 2 mm for a breakdown voltage of the order of 18 kV under pressure.
  • the counter-electrode 17 can be inserted into the sleeve 12 either during the manufacture thereof, for example by overmoulding in the material forming the sleeve, either after manufacture by piercing a orifice in the wall of the sleeve adapted to receive it. Constraints mechanics are then localized around the weak counter-electrode dimensions.
  • the ground electrode is shaped in the material of the cylinder head 18 of the engine connected to the mass.
  • a free portion of the counter-electrode 17, projecting from sleeve, is embedded in the metal forming the cylinder head ( Figure 3). This configuration is for example obtained by overmolding the candle in the metal.
  • the electrode of mass can be shaped into a metal base overmolded on the candle, the counter-electrode 17 flush with the surface of the sleeve coming in contact with the base connected to the ground, or a protruding part of the counter-electrode being embedded in the metal of the base.
  • FIG. 5 represents a cylinder head 18 of a combustion engine comprising two candles 10 according to the invention.
  • the breech 18 is crossed by an air injection duct 19 and an injection duct of fuel 20 opening into the combustion chamber of the engine (not shown)
  • Each candle 10 is placed in the breech 18 of so that the end face 13 of the sleeve 12 opens into the combustion chamber of the engine. This end face 13 can indifferently protrude slightly from the breech or be flush.
  • the orientation of the candle in the breech is chosen so that the ergot 16 be directed to the air / fuel mixture jet.
  • the ducts 19, 20 and the 10 candles are distributed around the rim of the breech, both ducts and two candles facing each other respectively.
  • the spurs 16 respective candles are directed towards each other.
  • This configuration is intended in particular, but not limited to, a small spark ignition engine, for which the ignition function is often difficult to solve because of fouling due to carburetion defects and oil lifts.
  • surface effect candles have the advantage of allow the creation of spark even in case of fouling, the spark also having a tendency to clean the surface of the insulation on its passage by burning the deposits.
  • each candle that is to say the shape of the asymmetrical portion 14 of the sleeve, is chosen from so that the material thicknesses between the candles 10 and the ducts 19, 20 are sufficient to ensure the robustness of the breech 18 while minimizing the space occupied by the footprint of the candle.
  • the maximum electrostatic field is located in the space separates the ends of the pin 16 and the ground electrode 17, such that so that the spark can form at the end of the pin 16.
  • presence of the spark changes the architecture of the field lines electrostatic so that it will move parallel to the against electrode 17 away from the pin 16, along the surface of the end face 13.
  • the counter electrode 17 has a section sufficiently weak, the spark is stabilized in direction and in position in space, which allows him to occupy the same position in the combustion chamber at each ignition.
  • the electrode 11 is connected to a terminal of positive polarity, so that when of the application of high voltage, this is the ground electrode 18 and not the central electrode 11 which wears.
  • Figures 6 to 9 show examples of configuration of cylinder heads for engines having air injection ducts and fuel and candles according to the invention.
  • the breeches are represented on the side of their face facing the chamber of combustion.
  • Figure 6 shows a cylinder head with four valves per cylinder and five candles 10, intended, for example, for indirect injection of fuel.
  • Two air injection ducts 19 and two ducts fuel injection 20 are distributed around the perimeter of the cylinder head, four candles 10 being placed between the four ducts near the periphery of the breech and a candle 10 being placed in the center of the cylinder head.
  • the lugs 16 of the four peripheral candles are directed towards the center of the breech, while that of the central candle is directed to one of the peripheral candles.
  • This configuration is particularly interesting to reduce the constraints adaptation of the compression ratio compared to rattling: the multi ignition provides five flame fronts that reach the area combustion chamber device faster than in the case of a simple central ignition.
  • the central candle can possibly be removed, since peripheral ignition is generally sufficient.
  • An example of a multi-ignition system that can be used is for example described in the document FR-2 792 374.
  • the notches 15 of the end of the peripheral candles have a shape suitable for optimum use of the projected area of the chamber.
  • the central candle can have a classic symmetry of revolution depending on the space available.
  • FIG. 7 represents a breech 18 similar to that of FIG. 6, but further having a central injector 21 for injection direct fuel.
  • the lug of the central candle is then directed towards the central injector 21.
  • This central candle can also be suppressed for favorable adaptations of the jets of the injector 21.
  • FIG. 8 shows a breech configuration 18 for a combustion chamber with three valves per cylinder and four candles ignition.
  • Two air injection ducts 19 and an injection duct 20 are regularly distributed on the periphery of the cylinder head, three candles 10 being distributed between the ducts nearby the periphery of the breech, their lug 16 being directed towards the center of the breech, a fourth central candle with three pins directed to the three peripheral candles.
  • the section of the face end of the candle has a shape adapted to the size, substantially in the shape of a triangle whose tips are directed as the lugs towards the peripheral candles.
  • One, two or three counter electrodes 17 can then be provided as needed. This configuration can be used for a direct injection engine of fuel, it is favorable to small bores.
  • the candle according to the invention can be advantageously used for a classic arrangement of central candle, for a room of four-valve combustion per cylinder, as shown in Figure 9.
  • the cylinder head has two air injection ducts 19 and two fuel injection pipes 20, the spark plug 10 according to the invention being placed in the center of the breech.
  • the end face of this last presents a four-pointed star-shaped section, each branch being directed between two injection ducts.
  • the central electrode of the candle has four pins 16 each directed towards a tip of the end face.
  • These four lugs may each be associated with a counter electrode 17, so that the spark bursts indifferently into one of the four directions, or one, two or three ground electrode (s) can be put in place to favor one, two or three direction (s) of propagation of the spark.

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  • Spark Plugs (AREA)

Abstract

The plug has a counter electrode (17) inserted in an insulating sleeve (12) surrounding a center electrode (11). An end of the electrode (17) is located at verticality of a pin (16) of the electrode (11) to generate an amplification of electrical field at the level of a pin end for sparking and guiding spark from the pin end towards a ground electrode at the time of application of a high voltage to the electrode (11). An independent claim is also included for a cylinder head of an internal combustion engine, comprising a spark plug.

Description

L'invention concerne une bougie d'allumage pour une culasse de moteur à combustion interne, destinée notamment à équiper un véhicule automobile. Elle concerne également une culasse pourvue d'une telle bougie.The invention relates to a spark plug for a cylinder head internal combustion engine, intended in particular to equip a motor vehicle. It also relates to a breech provided of such a candle.

L'invention concerne plus particulièrement une bougie à effet de surface, c'est-à-dire utilisant les effets d'amplification du champ électrique au voisinage d'une surface isolante.The invention more particularly relates to a candle effect of surface, that is to say using the effects of amplification of the field in the vicinity of an insulating surface.

Les propriétés des bougies à effet de surface sont connues pour permettre d'obtenir des étincelles de grande longueur, supérieure à 3 mm, au lieu de moins de 1 mm dans le cas des bougies classiques.The properties of surface effect candles are known for allow to obtain sparks of great length, superior to 3 mm, instead of less than 1 mm in the case of classic candles.

La plupart des bougies à effet de surface présentent une symétrie de révolution, tel que décrit par exemple dans le document FR-2 792 374. Toutefois, en raison de cette symétrie, l'étincelle prend naissance aléatoirement n'importe où sur le pourtour de la bougie, ce qui présente des inconvénients dans la rencontre entre le mélange carburé et l'étincelle initiatrice de la combustion, la bougie elle-même masquant une partie de la chambre de combustion à l'étincelle.Most surface effect candles are symmetrical revolution, as described for example in document FR-2 792 374. However, because of this symmetry, the spark is born randomly anywhere on the edge of the candle, which presents disadvantages in the meeting between the fuel mixture and the initiating spark of combustion, the candle itself masking part of the spark chamber.

Le document FR-2 816 119 décrit une bougie à effet de surface permettant d'orienter l'étincelle radialement par rapport à l'axe de la bougie ce qui permet d'éviter que la bougie ne masque une partie de la chambre à l'étincelle.Document FR-2,816,119 describes a surface effect candle to direct the spark radially relative to the axis of the candle which prevents the candle from obscuring part of the room with spark.

Un modèle de bougie de surface décrit dans ce document est représenté sur la figure 1. La bougie est conformée pour présenter une symétrie de révolution autour de son axe longitudinal. Elle comprend une électrode cylindrique 1 reliée électriquement à la masse, qui sert de culot métallique. Ce culot entoure une électrode haute tension 2 de forme cylindrique disposée en position centrale. L'électrode centrale 2 est isolée du culot 1 par l'intermédiaire d'un manchon isolant 3 de forme sensiblement cylindrique. L'extrémité inférieure du manchon 3 présente une forme de collerette circulaire 4 de diamètre supérieur au reste du manchon. La collerette 4 coopère sur l'un de ses côtés avec une contre électrode 5 en forme de rondelle, qui peut être encastrée dans le manchon, son côté opposé présentant une surface 6 orientée vers la chambre de combustion. La partie extrême de l'électrode centrale 2 présente une forme évasée radialement 7 qui chapeaute le manchon isolant 3. Le champ électrostatique au voisinage de la surface 6 est alors amplifié par la contre électrode 5 reliée à l'électrode de masse. Cette bougie est appelée bougie de surface à étincelle radiale dans la mesure où l'étincelle est créée sur la surface 6 de l'isolant, selon une direction sensiblement perpendiculaire à l'axe de la bougie. Toutefois, la partie en forme de collerette 4 d'une telle bougie doit présenter une faible épaisseur pour permettre une bonne amplification du champ électrostatique à la surface de l'isolant et une tension de claquage faible. Cette faible épaisseur la fragilise, ce qui nécessite un montage précis et une faible tolérance de l'usinage des pièces pour éviter l'application de contraintes mécaniques sur la collerette. En raison de cette fragilité, un montage de la bougie directement dans le culot ou la culasse, lors de la fonderie de ces pièces, entraíne une rupture fréquente de la collerette lors de la fabrication ou une fragilisation pouvant entraíner la détérioration de la bougie ultérieurement. La durée de vie de ces bougies une fois intégrées à la culasse est donc nettement insuffisante. Il est en effet difficilement pensable d'avoir à changer la culasse en raison d'une bougie défectueuse. Une telle bougie présente également l'inconvénient de ne pouvoir diriger l'étincelle dans une direction prédéterminée, celle-ci pouvant prendre naissance n'importe où sur le pourtour de la bougie, et notamment dans une direction opposée au mélange air/carburant.A model of surface candle described in this document is shown in Figure 1. The candle is shaped to present a symmetry of revolution around its longitudinal axis. She understands a cylindrical electrode 1 electrically connected to ground, which serves as metal base. This base surrounds a high voltage electrode 2 of cylindrical shape arranged in central position. The central electrode 2 is isolated from the base 1 via an insulating sleeve 3 of substantially cylindrical shape. The lower end of the sleeve 3 has a circular flange shape 4 of greater diameter than rest of the sleeve. The flange 4 cooperates on one of its sides with a counter electrode 5 in the form of a washer, which can be embedded in the sleeve, its opposite side having a surface 6 facing the combustion chamber. The extreme part of the central electrode 2 has a radially flared shape 7 which crowns the sleeve 3. The electrostatic field in the vicinity of surface 6 is then amplified by the counter electrode 5 connected to the ground electrode. This candle is called radial spark surface candle in the as the spark is created on the surface 6 of the insulation, according to a direction substantially perpendicular to the axis of the candle. However, flange-shaped part 4 of such a candle must have a low thickness to allow a good amplification of the field electrostatic on the surface of the insulation and a breakdown voltage low. This small thickness weakens it, which requires assembly accurate and low tolerance of machining parts to avoid the application of mechanical stresses on the collar. Due to this fragility, a mounting of the candle directly in the base or the breech, during the foundry of these parts, causes a break frequent collar during manufacture or embrittlement may cause deterioration of the candle later. The duration life of these candles once integrated into the cylinder head is clearly insufficient. It is hardly conceivable to have to change the breech because of a faulty candle. Such a candle presents also the disadvantage of not being able to direct the spark into a predetermined direction, which may originate anywhere where on the edge of the candle, and especially in one direction opposite to the air / fuel mixture.

L'invention vise à pallier ces inconvénients en proposant une bougie à effet de surface présentant une structure permettant de diriger l'étincelle dans au moins une direction prédéterminée tout en présentant une meilleure résistance mécanique de l'isolant. La bougie selon l'invention peut en outre être fabriquée à faible coût avec des tolérances plus élevées. La bougie selon l'invention est particulièrement bien adaptée à une utilisation intégrée à la culasse, sans toutefois s'y limiter.The aim of the invention is to overcome these disadvantages by proposing a surface effect candle having a structure for directing spark in at least one predetermined direction while having better mechanical strength of the insulation. The candle according to the invention may furthermore be manufactured at low cost with higher tolerances. The candle according to the invention is particularly well adapted to an integrated use in the cylinder head, without however limit.

A cet effet, un premier objet de l'invention concerne une bougie d'allumage à effet de surface pour culasse de moteur à combustion interne, comportant une électrode centrale entourée d'un manchon isolant et une électrode de masse entourant le manchon, ladite électrode centrale et ledit manchon s'étendant dans une direction privilégiée D, ledit manchon se terminant du côté destiné à être dirigé vers la culasse par une face d'extrémité sensiblement plane le long de laquelle une étincelle peut se propager et qui s'étend dans un plan P traversé par la direction D, ladite bougie étant caractérisée en ce que l'extrémité de l'électrode centrale fait saillie de ladite face d'extrémité du manchon et est pourvue d'au moins un ergot, chaque ergot s'étendant dans une direction distincte prédéterminée E sensiblement parallèle au plan P, et en ce qu'elle comprend au moins une contre-électrode de forme allongée insérée dans le manchon isolant et reliée à la masse, et dont une extrémité est localisée sensiblement à l'aplomb d'un ergot de l'électrode centrale, de manière à générer une amplification suffisante du champ électrique au niveau de l'extrémité dudit ergot pour faire jaillir et guider l'étincelle de ladite extrémité dudit ergot vers l'électrode de masse lors de l'application d'une haute tension à l'électrode centrale.For this purpose, a first object of the invention relates to a candle ignition system for combustion engine cylinder head internal, having a central electrode surrounded by a sleeve insulation and a ground electrode surrounding the sleeve, said central electrode and said sleeve extending in one direction D, said sleeve ending on the side intended to be directed towards the cylinder head by a substantially flat end face along which a spark can propagate and which extends in a plane P crossed by the direction D, said candle being characterized in that the end of the central electrode protrudes from said end face of sleeve and is provided with at least one lug, each lug extending in a predetermined distinct direction E substantially parallel to the plane P, and in that it comprises at least one counter-electrode of elongate shape inserted in the insulating sleeve and connected to the ground, and one end of which is located substantially in line with a pin of the central electrode, so as to generate sufficient amplification of the electric field at the end of said pin to make sprouting and guiding the spark from said end of said lug to the electrode of mass when applying a high voltage to the center electrode.

Il est ainsi possible de diriger l'étincelle dans au moins une direction souhaitée tout en renforçant la résistance mécanique du manchon. Les contraintes sont en effet localisées autour de la contre-électrode dans une petite partie du manchon dont la résistance mécanique est ainsi augmentée et dont la durée de vie peut atteindre celle du véhicule, permettant son intégration définitive à la culasse.It is thus possible to direct the spark in at least one desired direction while reinforcing the mechanical strength of the muff. The constraints are indeed localized around the counter-electrode in a small part of the sleeve whose resistance mechanics is thus increased and the life of which can reach that of the vehicle, allowing its final integration in the breech.

Dans une variante, ledit au moins un ergot est en contact avec ladite face d'extrémité du manchon afin de réduire la tension d'éclatement de la bougie.In a variant, said at least one lug is in contact with said end face of the sleeve to reduce tension bursting of the candle.

Dans une variante, l'électrode centrale est reliée à une borne de polarité positive, de sorte que c'est l'électrode de masse et non l'isolant ou l'électrode centrale, qui va s'user. Ce choix de polarité permet également de réduire sensiblement la tension de claquage. L'électrode de masse présentant un volume important par rapport à ces derniers, son usure n'affectera pas le fonctionnement de la bougie à long terme.In a variant, the central electrode is connected to a terminal of positive polarity, so that's the ground electrode and not the insulator or the central electrode, which will wear out. This choice of polarity allows also significantly reduce the breakdown voltage. The electrode mass with a large volume compared to these, its wear will not affect the operation of the candle in the long run.

Dans une variante, ladite au moins une contre-électrode est sensiblement en forme de barre ou de fil et/ou s'étend sensiblement parallèlement à un ergot. Cette configuration permet de faciliter son insertion dans le manchon de la bougie tout en réduisant encore les contraintes exercées par la contre-électrode sur le manchon environnant.In a variant, said at least one counter-electrode is substantially bar-shaped or wire-shaped and / or substantially parallel to a lug. This configuration makes it easier to insertion into the sleeve of the candle while further reducing the stresses exerted by the counter-electrode on the sleeve surrounding.

Dans une variante, la partie du manchon portant ladite face d'extrémité est de forme asymétrique et/ou présente une section de dimensions plus faibles relativement au reste du manchon. Il est ainsi possible de réduire l'encombrement de la bougie, ce qui permet de la loger plus facilement dans des culasses comportant de faibles volumes libres.In a variant, the portion of the sleeve bearing said face end is of asymmetrical shape and / or has a section of smaller dimensions relative to the rest of the sleeve. It is so possible to reduce the size of the candle, which allows the lodge more easily in cylinder heads with low volumes free.

Dans une variante, ledit au moins un ergot présente une forme allongée effilée en direction de son extrémité. Une telle forme permet de créer un effet de pointe favorisant la formation de l'étincelle à l'extrémité de l'ergot et limitant l'usure de cette dernière.In a variant, said at least one lug has a shape elongated tapered towards its end. Such a form allows create a peak effect that promotes spark formation at the end ergot and limiting the wear of the latter.

Dans un mode de réalisation, la bougie comporte en outre un culot métallique, ladite contre-électrode étant conformée dans la matière qui constitue le culot, et ladite au moins une contre-électrode étant en contact avec, ou partiellement noyée dans ladite matière. Cette dernière variante permet d'améliorer le contact entre la contre-électrode et l'électrode de masse.In one embodiment, the candle further comprises a metal base, said counter-electrode being shaped into the material which constitutes the pellet, and said at least one counterelectrode being in contact with, or partially embedded in, said material. This last variant makes it possible to improve the contact between the counterelectrode and the ground electrode.

Dans un autre mode de réalisation, la contre-électrode est directement conformée dans la matière qui constitue la culasse du moteur à combustion interne, et ladite au moins une contre-électrode étant en contact avec, ou partiellement noyée dans ladite matière.In another embodiment, the counter-electrode is directly conformed in the material constituting the breech of the internal combustion engine, and said at least one counter-electrode being in contact with, or partially embedded in, said material.

Un autre objet de l'invention concerne une culasse pour moteur à combustion de véhicule automobile, comprenant au moins une bougie selon l'invention, la géométrie et/ou les dimensions de la section de ladite face d'extrémité de ladite au moins une bougie étant choisies en fonction du nombre et de l'emplacement de conduites d'injection d'air et/ou carburant présentes dans la culasse.Another object of the invention relates to a cylinder head for combustion of a motor vehicle, comprising at least one candle according to the invention, the geometry and / or the dimensions of the section of said end face of said at least one candle being selected in function of number and location of air injection lines and / or fuel present in the cylinder head.

Dans un autre mode de réalisation, la culasse comprend au moins une bougie selon l'invention, et chaque bougie d'allumage est orientée de manière à ce que la direction (E) d'au moins un ergot soit dirigée vers le mélange air/carburant, afin que l'étincelle se propage suivant la direction (E).In another embodiment, the cylinder head comprises at minus one spark plug according to the invention, and each spark plug is oriented so that the direction (E) of at least one lug is directed to the air / fuel mixture, so that the spark spreads following the direction (E).

L'invention est maintenant décrite en référence aux dessins annexés, non limitatifs, dans lesquels :

  • la figure 1 représente une vue en coupe axiale d'une bougie à effet de surface à étincelle radiale selon l'art antérieur ;
  • la figure 2 représente une vue de face d'une bougie selon l'invention ;
  • la figure 3 représente une vue en coupe axiale d'une bougie de la figure 2 dans une culasse de moteur;
  • la figure 4 représente une vue en perspective d'une électrode centrale d'une bougie selon l'invention ;
  • la figure 5 représente une vue en perspective d'une culasse de moteur comportant deux bougies selon l'invention.
  • Les figures 6, à 9 représentent des vues de dessous de culasses de moteur comportant une ou plusieurs bougies selon l'invention.
The invention is now described with reference to the appended non-limiting drawings, in which:
  • Figure 1 shows an axial sectional view of a spark plug with a radial spark surface effect according to the prior art;
  • Figure 2 shows a front view of a candle according to the invention;
  • Figure 3 shows an axial sectional view of a candle of Figure 2 in a motor cylinder head;
  • FIG. 4 represents a perspective view of a central electrode of a candle according to the invention;
  • FIG. 5 represents a perspective view of an engine cylinder head comprising two spark plugs according to the invention.
  • Figures 6 to 9 show views of the bottom of motor yokes having one or more candles according to the invention.

Une bougie 10 selon l'invention est représentée sur les figures 2 et 3. Elle comporte une électrode centrale 11, sur laquelle sera appliquée une haute tension, entourée d'un manchon isolant 12 constitué d'une matière dont le coefficient diélectrique est supérieur à un, par exemple de la céramique. L'électrode 11 et le manchon 12 s'étendent dans une même direction privilégiée D.A candle 10 according to the invention is shown in FIGS. 3. It comprises a central electrode 11, on which will be applied a high voltage, surrounded by an insulating sleeve 12 consisting of a material whose dielectric coefficient is greater than one, for example ceramic. The electrode 11 and the sleeve 12 extend in a same privileged direction D.

Sur la majeure partie de sa longueur, le manchon 12 présente une symétrie de révolution dont l'axe est confondu avec la direction D. A son extrémité inférieure, le manchon comporte une face d'extrémité 13 sensiblement plane, le long de laquelle l'étincelle peut se propager. Cette face d'extrémité 13 s'étend dans un plan P traversé par la direction D. Ce plan P est perpendiculaire au plan de la feuille des figures 2 et 3. Une fois la bougie insérée dans une culasse, ce plan est confondu ou sensiblement parallèle avec le dessous de la culasse. L'angle d'inclinaison entre le plan P et la direction D sera alors déterminé en fonction de l'inclinaison de la bougie par rapport au dessous de la culasse dans laquelle elle doit être insérée. Ainsi, pour certaines culasses, le peu de place disponible au-dessus de la culasse nécessite l'insertion inclinée de la bougie par rapport à l'axe de la culasse, la face d'extrémité 13 étant placée sensiblement dans le prolongement de la surface du dessous de la culasse.Over most of its length, the sleeve 12 presents a symmetry of revolution whose axis is confused with the direction D. At its lower end, the sleeve has an end face 13 substantially flat, along which the spark can spread. This end face 13 extends in a plane P crossed by the direction D. This plane P is perpendicular to the plane of the sheet of Figures 2 and 3. Once the candle is inserted in a cylinder head, this plan is confused or substantially parallel with the underside of the breech. The angle of inclination between the plane P and the direction D will then be determined according to the inclination of the candle relative to below the breech in which it must be inserted. So, for some cylinder heads, the little available space above the cylinder head requires the inclined insertion of the candle with respect to the axis of the cylinder head, the end face 13 being placed substantially in the extension of the bottom surface of the cylinder head.

A proximité de sa face d'extrémité 13, le manchon 12 présente une partie de forme asymétrique 14. Cette partie asymétrique est par exemple obtenue en réalisant des échancrures 15 dans les parois latérales de la bougie. Dans le mode de réalisation des bougies représenté figures 2, 3 et 5 à 7, deux échancrures 15 sont réalisées, la section de la partie asymétrique 14 et la face d'extrémité 13 présentant alors sensiblement une forme de triangle aigu, le petit côté du triangle étant arrondi (figures 5 à 7). La section présente alors une surface plus petite que le reste du manchon. Une telle réduction de la section du manchon présente l'avantage de réduire l'encombrement de la bougie et de faciliter son insertion dans une culasse.Near its end face 13, the sleeve 12 presents an asymmetrically shaped portion 14. This asymmetrical portion is example obtained by making indentations 15 in the walls side of the candle. In the embodiment of the candles shown in FIGS. 2, 3 and 5 to 7, two indentations 15 are made, the section of the asymmetric portion 14 and the end face 13 having then substantially an acute triangle shape, the small side of the triangle being rounded (Figures 5 to 7). The section then presents a surface more small as the rest of the sleeve. Such a reduction in the section of the sleeve has the advantage of reducing the bulk of the candle and to facilitate its insertion in a breech.

L'électrode centrale 11 présente une forme de tige cylindrique dont l'extrémité inférieure présente un ergot 16 qui fait saillie de la face d'extrémité 13 du manchon (figures 2 à 4). Cet ergot 16 s'étend dans une direction E sécante de la direction D. Il présente une forme effilée en direction de son extrémité libre de manière à limiter son usure. L'électrode centrale 11 est insérée dans le manchon, par exemple lors de sa fabrication, de sorte que l'ergot 16 soit plaqué contre la face d'extrémité 13 du manchon et s'étende ainsi sensiblement dans le même plan que celle-ci. Dans l'exemple, il est dirigé vers l'angle aigu de la face d'extrémité 13 en forme de triangle (figures 5 à 7).The central electrode 11 has a cylindrical rod shape whose lower end has a lug 16 which protrudes from the face end 13 of the sleeve (Figures 2 to 4). This lug 16 extends into a direction E secant direction D. It has a tapered shape towards its free end so as to limit its wear. The central electrode 11 is inserted into the sleeve, for example during of its manufacture, so that the lug 16 is pressed against the face end 13 of the sleeve and thus extends substantially in the same plan as this one. In the example, it is directed to the acute angle of the end face 13 in the form of a triangle (Figures 5 to 7).

A proximité de sa face d'extrémité 13, le manchon isolant 12 comporte une contre-électrode 17 dont une extrémité est localisée sensiblement à l'aplomb de l'extrémité de l'ergot 16, et dont l'autre extrémité est reliée à une électrode de masse. Ainsi, la position de l'extrémité de cette électrode à l'aplomb de l'ergot permet la génération de l'étincelle à l'extrémité de l'ergot. Il n'est dès lors pas nécessaire que la contre-électrode 17 s'étende sur toute la périphérie du manchon, au contraire, il suffit qu'elle n'occupe qu'un faible volume du manchon, pourvu que son extrémité soit sensiblement à l'aplomb de l'extrémité de l'ergot.Near its end face 13, the insulating sleeve 12 has a counter-electrode 17, one end of which is located substantially perpendicular to the end of the lug 16, and the other end is connected to a ground electrode. Thus, the position of the end of this electrode in line with the pin allows the generation sparkle at the end of the pin. It is therefore not necessary that the counter-electrode 17 extends over the entire periphery of the sleeve, contrary, it suffices that it occupies only a small volume of the sleeve, provided that its end is substantially in line with the end of ergot.

De préférence, afin de limiter les contraintes et de faciliter son insertion dans le manchon, la contre-électrode 17 présente une forme allongée de faibles dimensions par rapport à la section du manchon. Elle est par exemple symétrique, en forme de barre cylindrique ou de fil de faible diamètre s'étendant sensiblement parallèlement à l'ergot 16 à une distance d de ce dernier. Les dimensions de la contre-électrode sont choisies en fonction de l'encombrement et afin de réduire les contraintes mécaniques et d'améliorer la stabilité de l'étincelle. Son diamètre peut ainsi varier de quelques microns à quelques millimètres. De préférence, la distance d n'est pas trop élevée afin de limiter la tension de claquage, par exemple de l'ordre de 1,5 à 2 mm pour une tension de claquage de l'ordre de 18kV sous pression.Preferably, in order to limit the stresses and facilitate its insertion into the sleeve, the counter-electrode 17 has an elongated shape of small dimensions relative to the section of the sleeve. It is for example symmetrical, in the form of a cylindrical bar or wire of small diameter extending substantially parallel to the lug 16 at a distance d from the latter. The dimensions of the counter-electrode are chosen according to the size and in order to reduce the mechanical stresses and to improve the stability of the spark. Its diameter can vary from a few microns to a few millimeters. Preferably, the distance d is not too high in order to limit the breakdown voltage, for example of the order of 1.5 to 2 mm for a breakdown voltage of the order of 18 kV under pressure.

La contre-électrode 17 peut être insérée dans le manchon 12 soit pendant la fabrication de celui-ci, par exemple par surmoulage dans le matériau formant le manchon, soit après la fabrication en perçant un orifice dans la paroi du manchon apte à la recevoir. Les contraintes mécaniques sont alors localisées autour de la contre-électrode de faibles dimensions.The counter-electrode 17 can be inserted into the sleeve 12 either during the manufacture thereof, for example by overmoulding in the material forming the sleeve, either after manufacture by piercing a orifice in the wall of the sleeve adapted to receive it. Constraints mechanics are then localized around the weak counter-electrode dimensions.

Il est dès lors possible de réduire considérablement les dimensions de l'ergot 16 et de la contre-électrode 17, ce qui rend possible la réduction des dimensions de la partie inférieure 14 du manchon dont la forme peut désormais être choisie en fonction de la structure de la culasse.It is therefore possible to reduce considerably the dimensions of the pin 16 and against the electrode 17, which makes possible the reduction of the dimensions of the lower 14 of the sleeve whose shape can now be chosen according to the breech structure.

Dans les exemples représentés, l'électrode de masse est conformée dans le matériau de la culasse 18 du moteur reliée à la masse. Afin d'assurer un contact étroit entre la contre-électrode 17 et la culasse 18, une partie libre de la contre-électrode 17, saillant du manchon, est noyée dans le métal formant la culasse (figure 3). Cette configuration est par exemple obtenue en surmoulant la bougie dans le métal.In the examples shown, the ground electrode is shaped in the material of the cylinder head 18 of the engine connected to the mass. In order to ensure a close contact between the counter electrode 17 and the breech 18, a free portion of the counter-electrode 17, projecting from sleeve, is embedded in the metal forming the cylinder head (Figure 3). This configuration is for example obtained by overmolding the candle in the metal.

On peut toutefois envisager d'autres modes de réalisation : l'extrémité de la contre-électrode 17, si elle présente une surface suffisante, peut par exemple affleurer la surface latérale du manchon 12 de la bougie, et venir en contact avec la culasse.However, other embodiments can be envisaged: the end of the counter electrode 17, if it has a surface sufficient, for example can be flush with the side surface of the sleeve 12 of the candle, and come into contact with the breech.

Dans un autre mode de réalisation non représenté, l'électrode de masse peut être conformée en un culot métallique surmoulé sur la bougie, la contre-électrode 17 affleurant la surface du manchon venant en contact avec le culot relié à la masse, ou bien, une partie saillante de la contre-électrode étant noyée dans le métal du culot.In another embodiment, not shown, the electrode of mass can be shaped into a metal base overmolded on the candle, the counter-electrode 17 flush with the surface of the sleeve coming in contact with the base connected to the ground, or a protruding part of the counter-electrode being embedded in the metal of the base.

La figure 5 représente une culasse 18 de moteur à combustion comportant deux bougies 10 selon l'invention. La culasse 18 est traversée par un conduit d'injection d'air 19 et un conduit d'injection de carburant 20 débouchant dans la chambre de combustion du moteur (non représentée). Chaque bougie 10 est placée dans la culasse 18 de sorte que la face d'extrémité 13 du manchon 12 débouche dans la chambre de combustion du moteur. Cette face d'extrémité 13 peut indifféremment faire saillie légèrement de la culasse ou être affleurante. L'orientation de la bougie dans la culasse est choisie de sorte que l'ergot 16 soit dirigé vers le jet de mélange air/ carburant.FIG. 5 represents a cylinder head 18 of a combustion engine comprising two candles 10 according to the invention. The breech 18 is crossed by an air injection duct 19 and an injection duct of fuel 20 opening into the combustion chamber of the engine (not shown) Each candle 10 is placed in the breech 18 of so that the end face 13 of the sleeve 12 opens into the combustion chamber of the engine. This end face 13 can indifferently protrude slightly from the breech or be flush. The orientation of the candle in the breech is chosen so that the ergot 16 be directed to the air / fuel mixture jet.

Dans l'exemple représenté figure 5, les conduits 19, 20 et les bougies 10 sont répartis sur le pourtour de la culasse, les deux conduits et les deux bougies se faisant face respectivement. Les ergots 16 respectifs des bougies sont dirigés l'un vers l'autre. Cette configuration est destinée notamment, sans toutefois s'y limiter, à un moteur de petite cylindrée à allumage commandé, pour lequel la fonction allumage est souvent difficile à résoudre en raison de l'encrassement dû aux défauts de carburation et aux remontées d'huile. Les bougies à effets de surface présentent en effet l'avantage de permettre la création d'étincelle même en cas d'encrassement, l'étincelle ayant en outre tendance à nettoyer la surface de l'isolant sur son passage en brûlant les dépôts.In the example represented in FIG. 5, the ducts 19, 20 and the 10 candles are distributed around the rim of the breech, both ducts and two candles facing each other respectively. The spurs 16 respective candles are directed towards each other. This configuration is intended in particular, but not limited to, a small spark ignition engine, for which the ignition function is often difficult to solve because of fouling due to carburetion defects and oil lifts. Indeed, surface effect candles have the advantage of allow the creation of spark even in case of fouling, the spark also having a tendency to clean the surface of the insulation on its passage by burning the deposits.

La forme de la section de l'extrémité de chaque bougie, c'est-à-dire la forme de la partie asymétrique 14 du manchon, est choisie de manière à ce que les épaisseurs de matière entre les bougies 10 et les conduits 19, 20 soient suffisantes pour assurer la robustesse de la culasse 18 tout en minimisant l'espace occupé par l'empreinte de la bougie.The shape of the end section of each candle, that is to say the shape of the asymmetrical portion 14 of the sleeve, is chosen from so that the material thicknesses between the candles 10 and the ducts 19, 20 are sufficient to ensure the robustness of the breech 18 while minimizing the space occupied by the footprint of the candle.

Lors de l'application d'une haute tension à l'électrode centrale 11, par l'intermédiaire d'un système d'allumage générateur de haute tension, le champ électrostatique maximal se situe dans l'espace qui sépare les extrémités de l'ergot 16 et de l'électrode de masse 17, de telle sorte que l'étincelle peut se former à l'extrémité de l'ergot 16. La présence de l'étincelle modifie l'architecture des lignes de champ électrostatiques de telle sorte qu'elle va se déplacer parallèlement à la contre-électrode 17 en s'éloignant de l'ergot 16, le long de la surface de la face d'extrémité 13. Si la contre-électrode 17 présente une section suffisamment faible, l'étincelle est stabilisée en direction et en position dans l'espace, ce qui lui permet d'occuper la même position dans la chambre de combustion à chaque allumage. De préférence, l'électrode centrale 11 est reliée à une borne de polarité positive, de sorte que lors de l'application de la haute tension, ce soit l'électrode de masse 18 et non l'électrode centrale 11 qui s'use.When applying a high voltage to the central electrode 11, via a high generator ignition system voltage, the maximum electrostatic field is located in the space separates the ends of the pin 16 and the ground electrode 17, such that so that the spark can form at the end of the pin 16. presence of the spark changes the architecture of the field lines electrostatic so that it will move parallel to the against electrode 17 away from the pin 16, along the surface of the end face 13. If the counter electrode 17 has a section sufficiently weak, the spark is stabilized in direction and in position in space, which allows him to occupy the same position in the combustion chamber at each ignition. Preferably, the electrode 11 is connected to a terminal of positive polarity, so that when of the application of high voltage, this is the ground electrode 18 and not the central electrode 11 which wears.

Les figures 6 à 9 représentent des exemples de configuration de culasses pour moteur comportant des conduits d'injection d'air et de carburant et des bougies selon l'invention. Les culasses sont représentées du côté de leur face dirigée vers la chambre de combustion. Figures 6 to 9 show examples of configuration of cylinder heads for engines having air injection ducts and fuel and candles according to the invention. The breeches are represented on the side of their face facing the chamber of combustion.

La figure 6 représente une culasse à quatre soupapes par cylindre et cinq bougies 10, destinée, par exemple, à une injection indirecte de carburant. Deux conduits d'injection d'air 19 et deux conduits d'injection de carburant 20 sont répartis sur le pourtour de la culasse, quatre bougies 10 étant placées entre les quatre conduits à proximité de la périphérie de la culasse et une bougie 10 étant placée au centre de la culasse. Les ergots 16 des quatre bougies périphériques sont dirigés vers le centre de la culasse, tandis que celui de la bougie centrale est dirigé vers l'une des bougies périphériques. Cette configuration est particulièrement intéressante pour faire reculer les contraintes d'adaptation des taux de compression par rapport au cliquetis : le multi allumage permet d'obtenir cinq fronts de flamme qui atteignent la zone périphérique de la chambre de combustion plus rapidement que dans le cas d'un simple allumage central. La bougie centrale peut éventuellement être supprimée, l'allumage périphérique étant en général suffisant. Un exemple de système multi allumage pouvant être utilisé est par exemple décrit dans le document FR-2 792 374. Les échancrures 15 de l'extrémité des bougies périphériques ont une forme adaptée à une utilisation optimale de la surface projetée de la chambre. La bougie centrale peut présenter une symétrie de révolution classique en fonction de la place disponible.Figure 6 shows a cylinder head with four valves per cylinder and five candles 10, intended, for example, for indirect injection of fuel. Two air injection ducts 19 and two ducts fuel injection 20 are distributed around the perimeter of the cylinder head, four candles 10 being placed between the four ducts near the periphery of the breech and a candle 10 being placed in the center of the cylinder head. The lugs 16 of the four peripheral candles are directed towards the center of the breech, while that of the central candle is directed to one of the peripheral candles. This configuration is particularly interesting to reduce the constraints adaptation of the compression ratio compared to rattling: the multi ignition provides five flame fronts that reach the area combustion chamber device faster than in the case of a simple central ignition. The central candle can possibly be removed, since peripheral ignition is generally sufficient. An example of a multi-ignition system that can be used is for example described in the document FR-2 792 374. The notches 15 of the end of the peripheral candles have a shape suitable for optimum use of the projected area of the chamber. The central candle can have a classic symmetry of revolution depending on the space available.

La figure 7 représente une culasse 18 similaire à celle de la figure 6, mais présentant en outre un injecteur central 21 pour l'injection directe de carburant. L'ergot de la bougie centrale est alors dirigé vers l'injecteur central 21. Cette bougie centrale peut également être supprimée pour des adaptations favorables des jets de l'injecteur 21.FIG. 7 represents a breech 18 similar to that of FIG. 6, but further having a central injector 21 for injection direct fuel. The lug of the central candle is then directed towards the central injector 21. This central candle can also be suppressed for favorable adaptations of the jets of the injector 21.

La figure 8 représente une configuration de culasse 18 pour une chambre de combustion à trois soupapes par cylindre et quatre bougies d'allumage. Deux conduits d'injection d'air 19 et un conduit d'injection de carburant 20 sont répartis régulièrement sur la périphérie de la culasse, trois bougies 10 étant réparties entre les conduits à proximité de la périphérie de la culasse, leur ergot 16 étant dirigé vers le centre de la culasse, une quatrième bougie centrale comportant trois ergots dirigés vers les trois bougies périphériques. La section de la face d'extrémité de la bougie présente une forme adaptée à l'encombrement, sensiblement en forme de triangle dont les pointes sont dirigées comme les ergots vers les bougies périphériques. Une, deux ou trois contre-électrodes 17 peuvent alors être prévues selon les besoins. Cette configuration peut être utilisée pour un moteur à injection directe de carburant, elle est favorable aux petits alésages.FIG. 8 shows a breech configuration 18 for a combustion chamber with three valves per cylinder and four candles ignition. Two air injection ducts 19 and an injection duct 20 are regularly distributed on the periphery of the cylinder head, three candles 10 being distributed between the ducts nearby the periphery of the breech, their lug 16 being directed towards the center of the breech, a fourth central candle with three pins directed to the three peripheral candles. The section of the face end of the candle has a shape adapted to the size, substantially in the shape of a triangle whose tips are directed as the lugs towards the peripheral candles. One, two or three counter electrodes 17 can then be provided as needed. This configuration can be used for a direct injection engine of fuel, it is favorable to small bores.

La bougie selon l'invention peut être avantageusement utilisée pour une disposition classique de bougie centrale, pour une chambre de combustion à quatre soupapes par cylindre, tel que représenté sur la figure 9. La culasse présente deux conduits d'injection d'air 19 et deux conduits d'injection de carburant 20, la bougie 10 selon l'invention étant placée au centre de la culasse. La face d'extrémité de cette dernière présente alors une section en forme d'étoile à quatre branches, chaque branche étant dirigée entre deux conduits d'injection. Dans l'exemple représenté, l'électrode centrale de la bougie présente quatre ergots 16 dirigés chacun vers une pointe de la face d'extrémité. Ces quatre ergots peuvent être chacun associés à une contre-électrode 17, de sorte que l'étincelle éclate indifféremment dans l'une des quatre directions, ou bien, une, deux ou trois électrode(s) de masse peut(peuvent) être mise(s) en place pour privilégier une, deux ou trois direction(s) de propagation de l'étincelle.The candle according to the invention can be advantageously used for a classic arrangement of central candle, for a room of four-valve combustion per cylinder, as shown in Figure 9. The cylinder head has two air injection ducts 19 and two fuel injection pipes 20, the spark plug 10 according to the invention being placed in the center of the breech. The end face of this last then presents a four-pointed star-shaped section, each branch being directed between two injection ducts. In the example shown, the central electrode of the candle has four pins 16 each directed towards a tip of the end face. These four lugs may each be associated with a counter electrode 17, so that the spark bursts indifferently into one of the four directions, or one, two or three ground electrode (s) can be put in place to favor one, two or three direction (s) of propagation of the spark.

Bien entendu, d'autres configurations de bougies avec des orientations différentes des ergots peuvent être envisagées en fonction du moteur et de son environnement, afin de diriger l'étincelle au plus près du mélange air/carburant.Of course, other configurations of candles with different orientations of the lugs can be envisaged according to of the engine and its environment, in order to direct the spark to the near the air / fuel mixture.

Claims (10)

Bougie d'allumage à effet de surface (10) pour culasse de moteur (18), comportant une électrode centrale (11) entourée d'un manchon isolant (12) et une électrode de masse (18) entourant le manchon, ladite électrode centrale et ledit manchon s'étendant dans une direction privilégiée (D), ledit manchon se terminant du côté destiné à être dirigé vers la culasse par une face d'extrémité (13) sensiblement plane le long de laquelle une étincelle peut se propager et qui s'étend dans un plan (P) traversé par la direction (D), caractérisée en ce que l'extrémité de ladite électrode centrale (11) fait saillie de ladite face d'extrémité du manchon et est pourvue d'au moins un ergot (16), chaque ergot (16) s'étendant dans une direction distincte prédéterminée (E) sensiblement parallèle au plan (P), et en ce qu'elle comprend au moins une contre-électrode (17) de forme allongée insérée dans le manchon isolant et reliée à la masse, et dont une extrémité est localisée sensiblement à l'aplomb d'un ergot (16) de l'électrode centrale, de manière à générer une amplification suffisante du champ électrique au niveau de l'extrémité dudit ergot pour faire jaillir et guider l'étincelle de ladite extrémité dudit ergot vers l'électrode de masse lors de l'application d'une haute tension à l'électrode centrale.A surface-effect spark plug (10) for an engine cylinder head (18), comprising a central electrode (11) surrounded by an insulating sleeve (12) and a ground electrode (18) surrounding the sleeve, said central electrode and said sleeve extending in a preferred direction (D), said sleeve terminating on the side intended to be directed towards the cylinder head by a substantially planar end face (13) along which a spark can propagate and which extends in a plane (P) traversed by the direction (D), characterized in that the end of said central electrode (11) projects from said end face of the sleeve and is provided with at least one lug ( 16), each lug (16) extending in a predetermined distinct direction (E) substantially parallel to the plane (P), and in that it comprises at least one elongated counter-electrode (17) inserted in the sleeve insulation and connected to the ground, and one end is loca located substantially vertically above a lug (16) of the central electrode, so as to generate a sufficient amplification of the electric field at the end of said lug to cause the spark of said end of said lug to spring and guide to the ground electrode when applying a high voltage to the center electrode. Bougie d'allumage selon la revendication 1, caractérisée en ce que ledit au moins un ergot (16) est en contact avec ladite face d'extrémité (13) du manchon.Spark plug according to claim 1, characterized in that said at least one lug (16) is in contact with said end face (13) of the sleeve. Bougie d'allumage selon la revendication 1 ou 2, caractérisée en ce que l'électrode centrale (11) est reliée à une borne de polarité positive.Spark plug according to Claim 1 or 2, characterized in that the central electrode (11) is connected to a positive polarity terminal. Bougie d'allumage selon des revendications 1 à 3, caractérisée en ce que ladite au moins une contre-électrode (17) est sensiblement en forme de barre ou de fil et/ou s'étend sensiblement parallèlement à un ergot.Spark plug according to claims 1 to 3, characterized in that said at least one counter electrode (17) is substantially rod-shaped or wire-shaped and / or extends substantially parallel to a pin. Bougie d'allumage selon l'une des revendications 1 à 4, caractérisée en ce que la partie du manchon (14) portant ladite face d'extrémité (13) est de forme asymétrique et/ou présente une section de dimensions plus faibles relativement au reste du manchon.Spark plug according to one of claims 1 to 4, characterized in that the portion of the sleeve (14) carrying said end face (13) is of asymmetrical shape and / or has a smaller section relative to the rest of the sleeve. Bougie d'allumage selon l'une des revendications 1 à 5, caractérisée en ce que ledit au moins un ergot (16) présente une forme allongée effilée en direction de son extrémité. Spark plug according to one of claims 1 to 5, characterized in that said at least one lug (16) has an elongated shape tapered towards its end. Bougie d'allumage selon l'une des revendications 1 à 6, caractérisée en ce que la contre-électrode (17) est directement conformée dans la matière qui constitue la culasse du moteur à combustion interne, et ladite au moins une contre-électrode (17) étant en contact avec, ou partiellement noyée dans ladite matière.Spark plug according to one of Claims 1 to 6, characterized in that the counter-electrode (17) is directly shaped in the material constituting the cylinder head of the internal combustion engine, and the at least one counter-electrode ( 17) being in contact with, or partially embedded in, said material. Bougie d'allumage selon l'une des revendications 1 à 6, caractérisée en ce qu'elle comporte en outre un culot métallique, ladite contre-électrode (17) étant conformée dans la matière qui constitue le culot, et ladite au moins une contre-électrode (17) étant en contact avec, ou partiellement noyée dans ladite matière.Spark plug according to one of claims 1 to 6, characterized in that it further comprises a metal base, said counter electrode (17) being shaped in the material constituting the base, and said at least one against -electrode (17) being in contact with, or partially embedded in, said material. Culasse pour moteur à combustion de véhicule automobile, caractérisée en ce qu'elle comprend au moins une bougie (10) selon l'une des revendications 1 à 8, et en ce que la géométrie et/ou les dimensions de la section de ladite face d'extrémité (13) de ladite au moins une bougie sont choisies en fonction du nombre et de l'emplacement de conduites d'injection d'air (19) et/ou carburant (20) présentes dans la culasse.Cylinder head for a combustion engine of a motor vehicle, characterized in that it comprises at least one spark plug (10) according to one of claims 1 to 8, and in that the geometry and / or the dimensions of the section of said face end portion (13) of said at least one spark plug are chosen according to the number and location of air injection pipes (19) and / or fuel (20) present in the cylinder head. Culasse pour moteur à combustion de véhicule automobile, caractérisée en ce qu'elle comprend au moins une bougie (10) selon l'une des revendications 1 à 8, et en ce que chaque bougie d'allumage est orientée de manière à ce que la direction (E) d'au moins un ergot (16) soit dirigée vers le mélange air/carburant, afin que l'étincelle se propage suivant la direction (E).Cylinder head for a combustion engine of a motor vehicle, characterized in that it comprises at least one spark plug (10) according to one of claims 1 to 8, and in that each spark plug is oriented so that the direction (E) of at least one lug (16) is directed towards the air / fuel mixture, so that the spark propagates in the direction (E).
EP04300674A 2003-10-24 2004-10-11 Surface discharge spark plug with a directed spark Withdrawn EP1526618A1 (en)

Applications Claiming Priority (2)

Application Number Priority Date Filing Date Title
FR0312478A FR2861509B1 (en) 2003-10-24 2003-10-24 SURFACE SPARKING IGNITION CANDLE WITH DIRECTED SPARK.
FR0312478 2003-10-24

Publications (1)

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EP1526618A1 true EP1526618A1 (en) 2005-04-27

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EP04300674A Withdrawn EP1526618A1 (en) 2003-10-24 2004-10-11 Surface discharge spark plug with a directed spark

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EP (1) EP1526618A1 (en)
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Cited By (1)

* Cited by examiner, † Cited by third party
Publication number Priority date Publication date Assignee Title
CN102105677A (en) * 2008-06-05 2011-06-22 雷诺股份公司 Power supply control for spark plug of internal combustion engine

Citations (5)

* Cited by examiner, † Cited by third party
Publication number Priority date Publication date Assignee Title
FR712855A (en) * 1931-02-28 1931-10-14 Spark plug improvements
US2734143A (en) * 1956-02-07 Sparking plugs for internal combustion
US2981860A (en) * 1959-07-07 1961-04-25 Globeunion Inc Spark plugs
FR2792374A1 (en) * 1999-04-15 2000-10-20 Renault Ignition system for a vehicle internal combustion engine, utilizes a surface-effect spark plug assembly and an inductive multi-spark or capacitive ignition system
FR2816119A1 (en) * 2000-10-27 2002-05-03 Renault RADIAL SPARKLE SURFACE CANDLE

Patent Citations (5)

* Cited by examiner, † Cited by third party
Publication number Priority date Publication date Assignee Title
US2734143A (en) * 1956-02-07 Sparking plugs for internal combustion
FR712855A (en) * 1931-02-28 1931-10-14 Spark plug improvements
US2981860A (en) * 1959-07-07 1961-04-25 Globeunion Inc Spark plugs
FR2792374A1 (en) * 1999-04-15 2000-10-20 Renault Ignition system for a vehicle internal combustion engine, utilizes a surface-effect spark plug assembly and an inductive multi-spark or capacitive ignition system
FR2816119A1 (en) * 2000-10-27 2002-05-03 Renault RADIAL SPARKLE SURFACE CANDLE

Cited By (2)

* Cited by examiner, † Cited by third party
Publication number Priority date Publication date Assignee Title
CN102105677A (en) * 2008-06-05 2011-06-22 雷诺股份公司 Power supply control for spark plug of internal combustion engine
CN102105677B (en) * 2008-06-05 2014-01-22 雷诺股份公司 Power supply control for spark plug of internal combustion engine

Also Published As

Publication number Publication date
FR2861509B1 (en) 2006-03-03
FR2861509A1 (en) 2005-04-29

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