WO2009101318A1 - Internal combustion engine comprising a combustion bowl for an injector of the ultrasonic type - Google Patents

Internal combustion engine comprising a combustion bowl for an injector of the ultrasonic type Download PDF

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Publication number
WO2009101318A1
WO2009101318A1 PCT/FR2009/050158 FR2009050158W WO2009101318A1 WO 2009101318 A1 WO2009101318 A1 WO 2009101318A1 FR 2009050158 W FR2009050158 W FR 2009050158W WO 2009101318 A1 WO2009101318 A1 WO 2009101318A1
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WO
WIPO (PCT)
Prior art keywords
fuel
injection
combustion bowl
bowl
combustion
Prior art date
Application number
PCT/FR2009/050158
Other languages
French (fr)
Inventor
Magali Besson
Fabien Defransure
Lysiane Grosjean
Original Assignee
Renault S.A.S.
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 Renault S.A.S. filed Critical Renault S.A.S.
Publication of WO2009101318A1 publication Critical patent/WO2009101318A1/en

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Classifications

    • F—MECHANICAL ENGINEERING; LIGHTING; HEATING; WEAPONS; BLASTING
    • F02—COMBUSTION ENGINES; HOT-GAS OR COMBUSTION-PRODUCT ENGINE PLANTS
    • F02B—INTERNAL-COMBUSTION PISTON ENGINES; COMBUSTION ENGINES IN GENERAL
    • F02B23/00—Other engines characterised by special shape or construction of combustion chambers to improve operation
    • F02B23/02—Other engines characterised by special shape or construction of combustion chambers to improve operation with compression ignition
    • F02B23/06—Other engines characterised by special shape or construction of combustion chambers to improve operation with compression ignition the combustion space being arranged in working piston
    • F02B23/0675—Other engines characterised by special shape or construction of combustion chambers to improve operation with compression ignition the combustion space being arranged in working piston the combustion space being substantially spherical, hemispherical, ellipsoid or parabolic
    • F—MECHANICAL ENGINEERING; LIGHTING; HEATING; WEAPONS; BLASTING
    • F02—COMBUSTION ENGINES; HOT-GAS OR COMBUSTION-PRODUCT ENGINE PLANTS
    • F02B—INTERNAL-COMBUSTION PISTON ENGINES; COMBUSTION ENGINES IN GENERAL
    • F02B23/00—Other engines characterised by special shape or construction of combustion chambers to improve operation
    • F02B23/02—Other engines characterised by special shape or construction of combustion chambers to improve operation with compression ignition
    • F02B23/06—Other engines characterised by special shape or construction of combustion chambers to improve operation with compression ignition the combustion space being arranged in working piston
    • F02B23/0645—Details related to the fuel injector or the fuel spray
    • F02B23/0648—Means or methods to improve the spray dispersion, evaporation or ignition
    • F—MECHANICAL ENGINEERING; LIGHTING; HEATING; WEAPONS; BLASTING
    • F02—COMBUSTION ENGINES; HOT-GAS OR COMBUSTION-PRODUCT ENGINE PLANTS
    • F02M—SUPPLYING COMBUSTION ENGINES IN GENERAL WITH COMBUSTIBLE MIXTURES OR CONSTITUENTS THEREOF
    • F02M27/00—Apparatus for treating combustion-air, fuel, or fuel-air mixture, by catalysts, electric means, magnetism, rays, sound waves, or the like
    • F02M27/08—Apparatus for treating combustion-air, fuel, or fuel-air mixture, by catalysts, electric means, magnetism, rays, sound waves, or the like by sonic or ultrasonic waves
    • F—MECHANICAL ENGINEERING; LIGHTING; HEATING; WEAPONS; BLASTING
    • F02—COMBUSTION ENGINES; HOT-GAS OR COMBUSTION-PRODUCT ENGINE PLANTS
    • F02M—SUPPLYING COMBUSTION ENGINES IN GENERAL WITH COMBUSTIBLE MIXTURES OR CONSTITUENTS THEREOF
    • F02M51/00—Fuel-injection apparatus characterised by being operated electrically
    • F02M51/06—Injectors peculiar thereto with means directly operating the valve needle
    • F02M51/0603—Injectors peculiar thereto with means directly operating the valve needle using piezoelectric or magnetostrictive operating means
    • F—MECHANICAL ENGINEERING; LIGHTING; HEATING; WEAPONS; BLASTING
    • F02—COMBUSTION ENGINES; HOT-GAS OR COMBUSTION-PRODUCT ENGINE PLANTS
    • F02M—SUPPLYING COMBUSTION ENGINES IN GENERAL WITH COMBUSTIBLE MIXTURES OR CONSTITUENTS THEREOF
    • F02M69/00—Low-pressure fuel-injection apparatus ; Apparatus with both continuous and intermittent injection; Apparatus injecting different types of fuel
    • F02M69/04—Injectors peculiar thereto
    • F02M69/041—Injectors peculiar thereto having vibrating means for atomizing the fuel, e.g. with sonic or ultrasonic vibrations
    • F—MECHANICAL ENGINEERING; LIGHTING; HEATING; WEAPONS; BLASTING
    • F02—COMBUSTION ENGINES; HOT-GAS OR COMBUSTION-PRODUCT ENGINE PLANTS
    • F02B—INTERNAL-COMBUSTION PISTON ENGINES; COMBUSTION ENGINES IN GENERAL
    • F02B2275/00—Other engines, components or details, not provided for in other groups of this subclass
    • F02B2275/14—Direct injection into combustion chamber
    • F—MECHANICAL ENGINEERING; LIGHTING; HEATING; WEAPONS; BLASTING
    • F02—COMBUSTION ENGINES; HOT-GAS OR COMBUSTION-PRODUCT ENGINE PLANTS
    • F02B—INTERNAL-COMBUSTION PISTON ENGINES; COMBUSTION ENGINES IN GENERAL
    • F02B3/00—Engines characterised by air compression and subsequent fuel addition
    • F02B3/06—Engines characterised by air compression and subsequent fuel addition with compression ignition
    • F—MECHANICAL ENGINEERING; LIGHTING; HEATING; WEAPONS; BLASTING
    • F02—COMBUSTION ENGINES; HOT-GAS OR COMBUSTION-PRODUCT ENGINE PLANTS
    • F02M—SUPPLYING COMBUSTION ENGINES IN GENERAL WITH COMBUSTIBLE MIXTURES OR CONSTITUENTS THEREOF
    • F02M2200/00—Details of fuel-injection apparatus, not otherwise provided for
    • F02M2200/21—Fuel-injection apparatus with piezoelectric or magnetostrictive elements
    • F—MECHANICAL ENGINEERING; LIGHTING; HEATING; WEAPONS; BLASTING
    • F02—COMBUSTION ENGINES; HOT-GAS OR COMBUSTION-PRODUCT ENGINE PLANTS
    • F02M—SUPPLYING COMBUSTION ENGINES IN GENERAL WITH COMBUSTIBLE MIXTURES OR CONSTITUENTS THEREOF
    • F02M61/00—Fuel-injectors not provided for in groups F02M39/00 - F02M57/00 or F02M67/00
    • F02M61/04—Fuel-injectors not provided for in groups F02M39/00 - F02M57/00 or F02M67/00 having valves, e.g. having a plurality of valves in series
    • F02M61/08—Fuel-injectors not provided for in groups F02M39/00 - F02M57/00 or F02M67/00 having valves, e.g. having a plurality of valves in series the valves opening in direction of fuel flow
    • Y—GENERAL TAGGING OF NEW TECHNOLOGICAL DEVELOPMENTS; GENERAL TAGGING OF CROSS-SECTIONAL TECHNOLOGIES SPANNING OVER SEVERAL SECTIONS OF THE IPC; TECHNICAL SUBJECTS COVERED BY FORMER USPC CROSS-REFERENCE ART COLLECTIONS [XRACs] AND DIGESTS
    • Y02—TECHNOLOGIES OR APPLICATIONS FOR MITIGATION OR ADAPTATION AGAINST CLIMATE CHANGE
    • Y02T—CLIMATE CHANGE MITIGATION TECHNOLOGIES RELATED TO TRANSPORTATION
    • Y02T10/00—Road transport of goods or passengers
    • Y02T10/10—Internal combustion engine [ICE] based vehicles
    • Y02T10/12—Improving ICE efficiencies

Definitions

  • the invention relates to an internal combustion engine comprising a combustion bowl for an ultrasonic-type injector.
  • the invention relates more particularly to an internal combustion engine with direct injection, in particular for a motor vehicle, comprising at least one cylinder and a combustion chamber which is delimited axially, in its upper part, by a lower face of an engine cylinder head. and in its lower part, by an upper face of a piston of vertical axis which slides alternately in the cylinder, wherein the piston comprises a combustion bowl which is delimited by an annular edge in the upper face of the piston and by an inner wall extending from this edge to a bottom, said annular edge forming with the upper face of the piston a flushing zone, in which the yoke carries at least one injection device capable of injecting the fuel towards the bowl of combustion.
  • Many internal combustion engines are known having a combustion chamber and more particularly a combustion bowl in the piston which is shaped according to the engine injection device with which it is associated.
  • the geometry of the combustion bowl is determined according to the characteristics of the injection device so as to obtain an air-fuel mixture to optimize the operation of the engine, including a reduction in fuel consumption and pollutant emissions.
  • the document EP-A-0.849.448 for example describes a combustion chamber for an internal combustion engine comprising an injector adapted to inject the fuel to the combustion bowl in the form of discrete jets.
  • the shutter means are for example constituted by a needle or a needle and are controlled to perform the injection, the fuel being sprayed in the form of discrete jets through holes arranged at the lower end of the nozzle. the nozzle of the injector.
  • the combustion bowl of the piston associated with such an injector is said to be "wide" in that it has an opening and a large diameter which are complementary to the jets determining an injection ply having a large opening angle which, determined by the intersection of a jet and the vertical axis XX of the piston, for example is greater than 60 °.
  • Such a combustion bowl is still geometrically characterized by a shallow depth and the presence of a central boss which extends vertically from the bottom of the bowl to the injector.
  • each jet In such a combustion chamber, the fuel from each of the jets penetrates inside the volume of the bowl to reach the inner wall and each jet then has two paths to mix with the intake air.
  • a portion of the fuel jet rises vertically above the impact zone with the internal wall of the combustion bowl so that this portion of the fuel is directed towards the hunting zone and the upper face of the piston.
  • the other part of the fuel rolls along the inner wall of the outer torus of the combustion bowl and then moves towards the center of the bowl having the central boss which it traverses the generally frustoconical outer surface to move vertically to the breech bearing the injector.
  • EP-A-1 170 522 describes an example of an ultrasonic-type fuel injector suitable for injecting the fuel in the form of an injection ply and not of discrete jets.
  • the implementation of such an ultrasonic type injector in a combustion chamber comprising for example a combustion bowl in the piston of the type described in document EP-A-0.849.448 is not satisfactory.
  • the penetration of fuel into the bowl is insufficient and therefore the operation of the intake air is not optimal which leads to a deteriorated mixing quality compared to a motor comprising a fuel injector with discrete jets.
  • the penetration of fuel injected by an ultrasonic injector is effected with a smaller amount of movement, that is to say a higher fuel mass injected at a lower speed, so that the winding of the fuel in the toroidal portion of the combustion bowl according to the second aforementioned path does not occur or little.
  • the air present in the combustion bowl is therefore poorly or poorly exploited and the mixture of the intake air and the fuel results mainly from the aspiration of the fuel by the hunting zone according to the aforementioned first path.
  • the phenomenon of hunting effect occurring only under specified conditions, in particular more or less 30 ° degree around the high engine point or PMH relative to the crankshaft, it is insufficient to obtain a satisfactory mix quality to improve engine performance while reducing pollutant emissions.
  • the invention therefore aims to overcome these disadvantages and to propose an internal combustion engine having a combustion chamber suitable for use in combination with an ultrasonic type injector.
  • the invention proposes an internal combustion engine of the type described above, characterized in that the injection device comprises at least one ultrasonic type injector comprising an actuator capable of controlling selectively shutter means for injecting the fuel in the form of a substantially conical injection ply having a small opening angle and in that the combustion bowl associated with the ultrasonic injector comprises an inner wall formed by a concave surface globally spherical.
  • the value of the opening angle of the injection ply is low so as to obtain an injection ply having a closed angle capable of increasing the penetration of the fuel by optimizing the spatial distribution of the momentum.
  • the combination according to the invention characterized by the association of the globally spherical combustion bowl with an ultrasonic-type injector, it optimizes the use of the air contained in the bowl which mixes with the fuel following movements. swirling caused by the interaction between the fuel layer and the globally spherical inner wall.
  • the mixture of air and fuel is thus obtained via a path following the aforementioned swirling movements and another path corresponding to the fuel directed towards the hunting zone.
  • the combustion bowl has an inner wall which, in axial section, has a circular profile
  • the combustion bowl has an inner wall which, in axial section, has a flat bottom which connects to the annular edge by a portion having a curvilinear profile;
  • the angle of the injection ply determined by the intersection of a mean injection axis of the injection ply and of the axis of the plunger is a so-called closed angle, the value of which is between ° and 50 ° so as to promote the penetration of fuel from the web into the combustion bowl;
  • the engine is of the compression ignition type;
  • the overall spherical surface forming the inner wall of the combustion bowl is shaped with a concavity determined so that, after coming into contact with the surface, at least a portion of the fuel is wound on itself in suitable vortex movements. optimizing the mixing of the fuel with the air present centrally in the bowl and another portion of the fuel travels the surface until it reaches the hunting zone to mix with the air included in the periphery of the cylinder;
  • the combustion bowl is centered relative to the top of the injection ply and the ultrasonic injector is centered on the axis of the piston;
  • the actuator of the ultrasonic injector is formed by a transducer that can be controlled to selectively perform fuel injection into the combustion bowl of the combustion chamber;
  • the actuator comprises at least one piezoelectric element, such as piezoelectric ceramics;
  • the actuator comprises at least one electrostatic element or at least one magnetostrictive element.
  • the single figure is a schematic view in axial section showing a combustion chamber of an internal combustion engine equipped with an ultrasonic type injector.
  • an internal combustion engine 10 in particular for a motor vehicle, which is a direct injection type engine.
  • the internal combustion engine 10 is a compression ignition engine, in particular a diesel engine.
  • the engine 10 comprises at least one cylinder 12 and an associated combustion chamber 14.
  • the combustion chamber 14 is delimited axially, in its upper part, by a lower face 16 of a cylinder head 18 of the engine 10 and, in its lower part, by an upper face 20 of a piston 22 of vertical axis XX which slide alternately in the cylinder 12.
  • the piston 22 comprises a combustion bowl 24 which is delimited by an edge 26, preferably annular, in the upper face 20 of the piston 22 and by an internal wall 28 which extends from this edge 26 to a bottom 30.
  • the annular edge 26 forms, with the upper face 20 of the piston 22, a hunting zone 32.
  • the cylinder head 18 of the engine 10 carries at least one injection device 34 comprising at least one injector 36 adapted to inject the fuel to the combustion bowl 24.
  • the injection device 34 constituted by at least one injector 36 of the ultrasonic type and the combustion bowl 24 associated with this ultrasonic injector 36 has an inner wall 28 which is formed by a concave surface 38 generally spherical.
  • the ultrasonic injector 36 comprises at least one actuator
  • the injection ply 44 is constituted as in EP-B1-1.1172.552 a cloud of fuel drops whose sizes are very similar and sufficiently small.
  • the opening angle ⁇ of the injection ply 44 is determined by the intersection of a mean injection axis A of the injection ply 44 with the vertical axis X-X of the piston 22.
  • the angle ⁇ of the injection ply 44 is a so-called closed angle, the value of which is advantageously between 20 ° and 50 ° so as to promote the penetration of the fuel from the ply 44 into the combustion bowl 24 by optimizing the exploitation made of the momentum of the fuel.
  • the combustion bowl 24 is centered with respect to the top of the injection ply 44.
  • the ultrasound injector 36 is here centered on the vertical axis X-X of the piston 22 and thus centered with respect to the combustion bowl 24.
  • the combustion bowl 24 has an inner wall 28 which, in axial section, has a substantially circular profile.
  • such a combustion bowl 24 is a shape that can be obtained by simple and inexpensive machining operations.
  • the spherical surface 38 according to the invention which forms the inner wall 28 of the combustion bowl 24 is shaped with a concavity determined according to the parameters of the injection ply 44 of the associated ultrasonic injector 36.
  • the spherical surface 38 of the combustion bowl 24 is shaped so that, after coming into contact with the surface 38 of the inner wall 28, at least a portion of the fuel is wound on itself in swirling movements illustrated in the figure by the arrows I and II and another part of the fuel runs along the arrow III illustrated in FIG. , the surface 38 until reaching the hunting zone 32 to mix with the air included periphery of the cylinder 12.
  • the swirling movements illustrated by the arrows I and II are obtained thanks to the specific spherical conformation of the internal wall 28 of the combustion bowl 24 which is determined to optimize the mixing of the fuel injected by the ultrasonic injector 36 with the assembly. of the air present centrally in the bowl 24.
  • the ultrasonic injector 36 mainly comprises, in addition to the actuator 40 and the shutter means 42, a housing 46 having an internal cavity 48 intended to be filled with pressurized fuel via an axial bore 49 for feeding the fuel adapted to be connected to a power supply circuit (not shown).
  • the housing 46 has at its lower end a nozzle 50 which is provided with a fuel injection orifice 52 with which the inner cavity 48 communicates.
  • the housing 46 has in the vicinity of the upper part of the nozzle 50 a stepped portion 54 on which is preferably disposed a support member 56 of damping material with which cooperates a portion of the actuator 40.
  • controllable transducer 58 for selectively injecting fuel into the chamber 14 within the combustion bowl 24.
  • such a transducer 58 constitutes an actuator 40 which is capable of generating vibrations in a vertical mode at ultrasonic frequencies, of the order of a few tens of kilohertz, for example between 10 and 50 kHz to allow for periods of time. minimum opening of the order of
  • the transducer 58 comprises a stepped portion 60 serving as a mechanical amplifier and ending in its upper part by a tube 62 in which the vibrations coming from the transducer 58 are transmitted.
  • the upper end of the tube 62 comprises a zone of attachment with a rod 64 and to which are transmitted the axial vibrations in the vertical direction of the transducer 58.
  • the rod 64 is mounted vertically movable inside the nozzle 50 and comprises a lower end 66 of frustoconical shape intended to cooperate selectively with a complementary seat 68 surrounding the injection port 52 to form a valve adapted to form shutter means 42 according to whether it occupies an open or closed position.
  • the support element 56 is able to exert an elastic restoring force tending to move the transducer 58 away from the nozzle 50 in order to resiliently return the frustoconical end.
  • the actuator 40 formed by the transducer 58 comprises at least one piezoelectric element 70, such as piezoelectric ceramics.
  • the actuator 40 formed by the transducer 58 comprises at least one electrostatic element or at least one magnetostrictive element.
  • Such elements are likely to deform in the vertical direction in response to the application of an electric or magnetic field.

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  • Engineering & Computer Science (AREA)
  • Chemical & Material Sciences (AREA)
  • Combustion & Propulsion (AREA)
  • Mechanical Engineering (AREA)
  • General Engineering & Computer Science (AREA)
  • Chemical Kinetics & Catalysis (AREA)
  • Dispersion Chemistry (AREA)
  • Fuel-Injection Apparatus (AREA)

Abstract

The invention relates to a direct‑injection internal combustion engine (10) comprising at least one cylinder (12), one combustion chamber (14) and one injection device (34) able to inject the fuel towards a combustion bowl (24), characterized in that the injection device (34) comprises at least one ultrasonic injector (36) comprising an actuator (40) able at an ultrasonic excitation frequency selectively to control shutter means (42) in order to inject the fuel in the form of a substantially conical injection pattern (44) having a small cone angle (α) and in that the combustion bowl (24) associated with the ultrasonic injector (36) has an internal wall (28) formed of a concave surface (38) that is spherical overall.

Description

"Moteur à combustion i nterne comportant un bol de combustion pour un i njecteur de type u ltrasonore" "Internal Combustion Engine With Combustion Bowl For U-Controlled I njector"
L'invention concerne un moteur à combustion interne comportant un bol de combustion pour un injecteur de type ultrasonore.The invention relates to an internal combustion engine comprising a combustion bowl for an ultrasonic-type injector.
L'invention concerne plus particulièrement un moteur à combustion interne à injection directe, notamment pour véhicule automobile, comportant au moins un cylindre et une chambre de combustion qui est délimitée axialement, dans sa partie supérieure, par une face inférieure d'une culasse d u moteur et, dans sa partie inférieure, par une face supérieure d'un piston d'axe vertical qui coulisse alternativement dans le cylindre, dans lequel le piston comporte un bol de combustion qui est délimité par un bord annulaire dans la face supérieure du piston et par une paroi interne qui s'étend depuis ce bord jusqu'à un fond, ledit bord annulaire formant avec la face supérieure du piston une zone de chasse, dans lequel la culasse porte au moins un dispositif d'injection apte à injecter le carburant vers le bol de combustion . On connaît de nombreux moteurs à combustion interne comportant une chambre de combustion et plus particulièrement un bol de combustion dans le piston qui est conformée en fonction du dispositif d'injection du moteur auquel il est associé.The invention relates more particularly to an internal combustion engine with direct injection, in particular for a motor vehicle, comprising at least one cylinder and a combustion chamber which is delimited axially, in its upper part, by a lower face of an engine cylinder head. and in its lower part, by an upper face of a piston of vertical axis which slides alternately in the cylinder, wherein the piston comprises a combustion bowl which is delimited by an annular edge in the upper face of the piston and by an inner wall extending from this edge to a bottom, said annular edge forming with the upper face of the piston a flushing zone, in which the yoke carries at least one injection device capable of injecting the fuel towards the bowl of combustion. Many internal combustion engines are known having a combustion chamber and more particularly a combustion bowl in the piston which is shaped according to the engine injection device with which it is associated.
La géométrie du bol de combustion est déterminée en fonction des caractéristiques du dispositif d'injection de manière à obtenir un mélange air-carburant propre à optimiser le fonctionnement du moteur, notamment une réduction de la consommation de carburant comme des émissions de polluants.The geometry of the combustion bowl is determined according to the characteristics of the injection device so as to obtain an air-fuel mixture to optimize the operation of the engine, including a reduction in fuel consumption and pollutant emissions.
Le document EP-A-0.849.448 décrit par exemple une chambre de combustion pour un moteur à combustion interne comportant un injecteur apte à injecter le carburant vers le bol de combustion sous la forme de jets discrets. Dans un tel injecteur, les moyens obturateurs sont par exemple constitués par un pointeau ou une aiguille et sont commandés pour réaliser l'injection, le carburant étant pulvérisé sous la forme de jets discrets par l'intermédiaire de trous disposés à l'extrémité inférieure de la buse de l'injecteur.The document EP-A-0.849.448 for example describes a combustion chamber for an internal combustion engine comprising an injector adapted to inject the fuel to the combustion bowl in the form of discrete jets. In such an injector, the shutter means are for example constituted by a needle or a needle and are controlled to perform the injection, the fuel being sprayed in the form of discrete jets through holes arranged at the lower end of the nozzle. the nozzle of the injector.
Le bol de combustion du piston associé à un tel injecteur est dit "large" en ce qu'il présente une ouverture et un diamètre important qui sont complémentaires des jets déterminant une nappe d'injection présentant un grand angle d'ouverture qui, déterminé par l'intersection d'un jet et de l'axe vertical X-X du piston , est par exemple supérieur à 60° .The combustion bowl of the piston associated with such an injector is said to be "wide" in that it has an opening and a large diameter which are complementary to the jets determining an injection ply having a large opening angle which, determined by the intersection of a jet and the vertical axis XX of the piston, for example is greater than 60 °.
Un tel bol de combustion se caractérise encore géométriquement par une faible profondeur et la présence d'un bossage central qui s'étend verticalement à partir du fond du bol vers l'injecteur.Such a combustion bowl is still geometrically characterized by a shallow depth and the presence of a central boss which extends vertically from the bottom of the bowl to the injector.
Dans une telle chambre de combustion , le carburant issu de chacun des jets pénètre à l'intérieur du volume du bol jusqu'à atteindre la paroi interne et chaque jet dispose alors de deux chemin pour se mélanger avec l'air d'admission . Suivant un premier chemin , une partie du jet de carburant remonte verticalement au dessus de la zone d'impact avec la paroi interne du bol de combustion de sorte que cette partie du carburant est dirigée vers la zone de chasse et la face supérieure du piston . Suivant un deuxième chemin , l'autre partie du carburant s'enroule en suivant la paroi interne du tore extérieur du bol de combustion puis se dirige vers le centre du bol comportant le bossage central dont il parcourt la surface externe globalement tronconique pour se diriger verticalement vers la culasse portant l'injecteur.In such a combustion chamber, the fuel from each of the jets penetrates inside the volume of the bowl to reach the inner wall and each jet then has two paths to mix with the intake air. According to a first path, a portion of the fuel jet rises vertically above the impact zone with the internal wall of the combustion bowl so that this portion of the fuel is directed towards the hunting zone and the upper face of the piston. Following a second path, the other part of the fuel rolls along the inner wall of the outer torus of the combustion bowl and then moves towards the center of the bowl having the central boss which it traverses the generally frustoconical outer surface to move vertically to the breech bearing the injector.
Le document EP-A-1 .172.552 décrit un exemple d'injecteur de carburant de type ultrasonore apte à injecter le carburant sous la forme d'une nappe d'injection et non pas de jets discrets. La mise en œuvre d'un tel injecteur de type ultrasonore dans une chambre de combustion comportant par exemple un bol de combustion dans le piston du type de celui décrit dans le document EP-A-0.849.448 n'est pas satisfaisante. Or, avec un tel injecteur ultrasonore, la pénétration du carburant dans le bol est insuffisante et par conséquent l'exploitation de l'air d'admission n'est pas optimale ce qui conduit à une qualité de mélange dégradée par rapport à un moteur comportant un injecteur de carburant à jets discrets. En effet, la pénétration du carburant injecté par un injecteur ultrasonore s'effectue avec une moindre quantité de mouvement, c'est-à-dire une masse de carburant supérieure injectée à une vitesse inférieure, de sorte que l'enroulement du carburant dans la partie toroïdale du bol de combustion selon le deuxième chemin précité ne se produit pas ou peu .EP-A-1 170 522 describes an example of an ultrasonic-type fuel injector suitable for injecting the fuel in the form of an injection ply and not of discrete jets. The implementation of such an ultrasonic type injector in a combustion chamber comprising for example a combustion bowl in the piston of the type described in document EP-A-0.849.448 is not satisfactory. However, with such an ultrasonic injector, the penetration of fuel into the bowl is insufficient and therefore the operation of the intake air is not optimal which leads to a deteriorated mixing quality compared to a motor comprising a fuel injector with discrete jets. Indeed, the penetration of fuel injected by an ultrasonic injector is effected with a smaller amount of movement, that is to say a higher fuel mass injected at a lower speed, so that the winding of the fuel in the toroidal portion of the combustion bowl according to the second aforementioned path does not occur or little.
L'air présent dans le bol de combustion est donc mal ou peu exploité et le mélange de l'air d'admission et du carburant résulte principalement de l'aspiration du carburant par la zone de chasse selon le premier chemin précité. Toutefois, le phénomène d'effet de chasse ne se produisant que dans des conditions déterminées, notamment plus ou moins 30° degré autour du point moteur haut ou PMH par rapport au vilebrequin , il est insuffisant pour obtenir une qualité de mélange satisfaisante propre à améliorer les performances du moteur tout en réduisant les émissions de polluants.The air present in the combustion bowl is therefore poorly or poorly exploited and the mixture of the intake air and the fuel results mainly from the aspiration of the fuel by the hunting zone according to the aforementioned first path. However, the phenomenon of hunting effect occurring only under specified conditions, in particular more or less 30 ° degree around the high engine point or PMH relative to the crankshaft, it is insufficient to obtain a satisfactory mix quality to improve engine performance while reducing pollutant emissions.
L'invention a donc notamment pour but de résoudre ces inconvénients et de proposer un moteur à combustion interne comportant une chambre de combustion propre à être utilisée en combinaison avec un injecteur de type ultrasonore. Dans ce but, l'invention propose un moteur à combustion interne du type décrit précédemment, caractérisé en ce que le dispositif d'injection comporte au moins un injecteur du type ultrasonore comportant un actuateur apte à commander sélectivement des moyens obturateurs pour injecter le carburant sous la forme d'une nappe d'injection sensiblement conique présentant un faible angle d'ouverture et en ce que le bol de combustion associé à l'injecteur ultrasonore comporte une paroi interne formée par une surface concave globalement sphérique.The invention therefore aims to overcome these disadvantages and to propose an internal combustion engine having a combustion chamber suitable for use in combination with an ultrasonic type injector. For this purpose, the invention proposes an internal combustion engine of the type described above, characterized in that the injection device comprises at least one ultrasonic type injector comprising an actuator capable of controlling selectively shutter means for injecting the fuel in the form of a substantially conical injection ply having a small opening angle and in that the combustion bowl associated with the ultrasonic injector comprises an inner wall formed by a concave surface globally spherical.
Avantageusement, la valeur de l'angle d'ouverture de la nappe d'injection est faible de manière à obtenir une nappe d'injection présentant un angle fermé propre à augmenter la pénétration du carburant en optimisant la répartition spatiale de la quantité de mouvement.Advantageously, the value of the opening angle of the injection ply is low so as to obtain an injection ply having a closed angle capable of increasing the penetration of the fuel by optimizing the spatial distribution of the momentum.
Grâce à la combinaison selon l'invention caractérisée par l'association du bol de combustion de forme globalement sphérique avec un injecteur de type ultrasonore, on optimise l'exploitation de l'air contenu dans le bol qui se mélange avec le carburant suivant des mouvements tourbillonnaires provoqués par l'interaction entre la nappe de carburant et la paroi interne globalement sphérique.Thanks to the combination according to the invention characterized by the association of the globally spherical combustion bowl with an ultrasonic-type injector, it optimizes the use of the air contained in the bowl which mixes with the fuel following movements. swirling caused by the interaction between the fuel layer and the globally spherical inner wall.
Avantageusement, le mélange de l'air et du carburant est donc obtenu par l'intermédiaire d'un chemin suivant les mouvements tourbillonnaires précités et d'un autre chemin correspondant à la partir du carburant dirigée vers la zone de chasse.Advantageously, the mixture of air and fuel is thus obtained via a path following the aforementioned swirling movements and another path corresponding to the fuel directed towards the hunting zone.
Selon d'autres caractéristiques de l'invention :According to other features of the invention:
- le bol de combustion comporte une paroi interne qui, en coupe axiale, présente un profil circulaire ;- The combustion bowl has an inner wall which, in axial section, has a circular profile;
- le bol de combustion comporte une paroi interne qui, en coupe axiale, présente un fond plat qui se raccorde au bord annulaire par une portion présentant un profil curviligne ;- The combustion bowl has an inner wall which, in axial section, has a flat bottom which connects to the annular edge by a portion having a curvilinear profile;
- l'angle de la nappe d'injection déterminé par l'intersection d'un axe moyen d'injection de la nappe d'injection et de l'axe du piston est un angle, dit fermé, dont la valeur est comprise entre 20° et 50° de manière à favoriser la pénétration du carburant de la nappe dans le bol de combustion ; - le moteur est du type à allumage par compression ;the angle of the injection ply determined by the intersection of a mean injection axis of the injection ply and of the axis of the plunger is a so-called closed angle, the value of which is between ° and 50 ° so as to promote the penetration of fuel from the web into the combustion bowl; the engine is of the compression ignition type;
- la surface globalement sphérique formant la paroi interne du bol de combustion est conformée avec une concavité déterminée de manière que, après leur entrée en contact avec la surface, au moins une partie du carburant s'enroule sur lui-même suivant des mouvements tourbillonnaires aptes à optimiser le mélange du carburant avec l'air présent centralement dans le bol et qu'une autre partie du carburant parcourt la surface jusqu'à atteindre la zone de chasse pour s'y mélanger avec l'air compris en périphérie du cylindre ;- The overall spherical surface forming the inner wall of the combustion bowl is shaped with a concavity determined so that, after coming into contact with the surface, at least a portion of the fuel is wound on itself in suitable vortex movements. optimizing the mixing of the fuel with the air present centrally in the bowl and another portion of the fuel travels the surface until it reaches the hunting zone to mix with the air included in the periphery of the cylinder;
- le bol de combustion est centré par rapport au sommet de la nappe d'injection et que l'injecteur ultrasonore est centré sur l'axe du piston ;- The combustion bowl is centered relative to the top of the injection ply and the ultrasonic injector is centered on the axis of the piston;
- l'actuateur de l'injecteur ultrasonore est formé par un transducteur apte à être commandé pour réaliser sélectivement l'injection de carburant dans le bol de combustion de la chambre de combustion ; l'actuateur comporte au moins un élément piézoélectrique, tel que des céramiques piézo-électriques ; - l'actuateur comporte au moins un élément électrostatique ou au moins un élément magnétostrictif.the actuator of the ultrasonic injector is formed by a transducer that can be controlled to selectively perform fuel injection into the combustion bowl of the combustion chamber; the actuator comprises at least one piezoelectric element, such as piezoelectric ceramics; the actuator comprises at least one electrostatic element or at least one magnetostrictive element.
D'autres caractéristiques et avantages de l'invention apparaîtront à la lecture de la description détaillée qui suit pour la compréhension de laquelle on se reportera à la figure unique annexée.Other features and advantages of the invention will appear on reading the detailed description which follows for the understanding of which reference will be made to the single appended figure.
La figure unique est une vue schématique en coupe axiale représentant une chambre de combustion d'un moteur à combustion interne équipé d'un injecteur de type ultrasonore.The single figure is a schematic view in axial section showing a combustion chamber of an internal combustion engine equipped with an ultrasonic type injector.
Dans la description qui va suivre et les revendications, on utilisera à titre non limitatif les termes, tels que "supérieure" etIn the following description and the claims, use will be made without limitation of the terms, such as "superior" and
"inférieure", "axial" et "radial" et les orientations "longitudinale","lower", "axial" and "radial" and the "longitudinal" orientations,
"verticale" et "transversale" pour désigner respectivement des éléments selon les définitions données dans la description et par rapport au trièdre (L, V, T) représenté sur la figure."vertical" and "transverse" to designate respectively elements according to the definitions given in the description and with respect to the trihedron (L, V, T) shown in the figure.
On a représenté sur la figure, un moteur 10 à combustion interne, notamment pour véhicule automobile, qui est un moteur du type à injection directe.There is shown in the figure, an internal combustion engine 10, in particular for a motor vehicle, which is a direct injection type engine.
De préférence, le moteur 10 à combustion interne est moteur à allumage par compression , en particulier un moteur Diesel .Preferably, the internal combustion engine 10 is a compression ignition engine, in particular a diesel engine.
Le moteur 10 comporte au moins un cylindre 12 et une chambre de combustion 14 associée.The engine 10 comprises at least one cylinder 12 and an associated combustion chamber 14.
La chambre de combustion 14 est délimitée axialement, dans sa partie supérieure, par une face inférieure 16 d'une culasse 18 du moteur 10 et, dans sa partie inférieure, par une face supérieure 20 d'un piston 22 d'axe vertical X-X qui coulisse alternativement dans le cylindre 12.The combustion chamber 14 is delimited axially, in its upper part, by a lower face 16 of a cylinder head 18 of the engine 10 and, in its lower part, by an upper face 20 of a piston 22 of vertical axis XX which slide alternately in the cylinder 12.
Le piston 22 comporte un bol de combustion 24 qui est délimité par un bord 26, de préférence annulaire, dans la face supérieure 20 du piston 22 et par une paroi interne 28 qui s'étend depuis ce bord 26 jusqu'à un fond 30. Le bord annulaire 26 forme, avec la face supérieure 20 du piston 22, une zone de chasse 32.The piston 22 comprises a combustion bowl 24 which is delimited by an edge 26, preferably annular, in the upper face 20 of the piston 22 and by an internal wall 28 which extends from this edge 26 to a bottom 30. The annular edge 26 forms, with the upper face 20 of the piston 22, a hunting zone 32.
La culasse 18 du moteur 10 porte au moins un dispositif d'injection 34 comportant au moins un injecteur 36 apte à injecter le carburant vers le bol de combustion 24. Conformément à l'invention , le dispositif d'injection 34 constitué par au moins un injecteur 36 du type ultrasonore et le bol de combustion 24 associé à cet injecteur ultrasonore 36 comporte une paroi interne 28 qui est formée par une surface concave 38 globalement sphérique. L'injecteur ultrasonore 36 comporte au moins un actuateurThe cylinder head 18 of the engine 10 carries at least one injection device 34 comprising at least one injector 36 adapted to inject the fuel to the combustion bowl 24. According to the invention, the injection device 34 constituted by at least one injector 36 of the ultrasonic type and the combustion bowl 24 associated with this ultrasonic injector 36 has an inner wall 28 which is formed by a concave surface 38 generally spherical. The ultrasonic injector 36 comprises at least one actuator
40 apte à commander à fréquence d'excitation ultrasonore sélectivement des moyens obturateur 42 pour injecter le carburant sous la forme d'une nappe d'injection 44 sensiblement conique présentant un faible angle d'ouverture "α".40 able to control at ultrasonically excitation frequency selectively shutter means 42 for injecting the fuel in the form of a substantially conical injection ply 44 having a small opening angle "α".
La nappe d'injection 44 est constituée comme dans le brevet EP-B1 -1 .172.552 d'un nuage de gouttes de carburant dont les tailles sont très voisines et suffisamment petites.The injection ply 44 is constituted as in EP-B1-1.1172.552 a cloud of fuel drops whose sizes are very similar and sufficiently small.
L'angle d'ouverture α de la nappe d'injection 44 est déterminé par l'intersection d'un axe moyen d'injection A de la nappe d'injection 44 avec l'axe vertical X-X du piston 22.The opening angle α of the injection ply 44 is determined by the intersection of a mean injection axis A of the injection ply 44 with the vertical axis X-X of the piston 22.
L'angle α de la nappe d'injection 44 est un angle, dit fermé, dont la valeur est avantageusement comprise entre 20° et 50° de manière à favoriser la pénétration du carburant de la nappe 44 dans le bol de combustion 24 en optimisant l'exploitation faite de la quantité de mouvement du carburant.The angle α of the injection ply 44 is a so-called closed angle, the value of which is advantageously between 20 ° and 50 ° so as to promote the penetration of the fuel from the ply 44 into the combustion bowl 24 by optimizing the exploitation made of the momentum of the fuel.
De préférence, le bol de combustion 24 est centré par rapport au sommet de la nappe d'injection 44.Preferably, the combustion bowl 24 is centered with respect to the top of the injection ply 44.
Avantageusement, l'injecteur ultrasonore 36 est ici centré sur l'axe vertical X-X du piston 22 et donc centré par rapport au bol de combustion 24.Advantageously, the ultrasound injector 36 is here centered on the vertical axis X-X of the piston 22 and thus centered with respect to the combustion bowl 24.
Selon un mode de réalisation préféré de l'invention illustré sur la figure, le bol de combustion 24 comporte une paroi interne 28 qui, en coupe axiale, présente un profil sensiblement circulaire.According to a preferred embodiment of the invention illustrated in the figure, the combustion bowl 24 has an inner wall 28 which, in axial section, has a substantially circular profile.
Avantageusement, un tel bol de combustion 24 est une forme susceptible d'être obtenue par des opérations d'usinage simples et peu coûteuses.Advantageously, such a combustion bowl 24 is a shape that can be obtained by simple and inexpensive machining operations.
Avantageusement, la surface sphérique 38 selon l'invention qui forme la paroi interne 28 du bol de combustion 24 est conformée avec une concavité déterminée en fonction des paramètres de la nappe d'injection 44 de l'injecteur ultrasonore 36 associé.Advantageously, the spherical surface 38 according to the invention which forms the inner wall 28 of the combustion bowl 24 is shaped with a concavity determined according to the parameters of the injection ply 44 of the associated ultrasonic injector 36.
Conformément aux enseignements de l'invention, la surface sphérique 38 du bol de combustion 24 est conformée de manière que, après leur entrée en contact avec la surface 38 de la paroi interne 28, au moins une partie du carburant s'enroule sur lui-même suivant des mouvements tourbillonnaires illustrés sur la figure par les flèches I et I I et qu'une autre partie du carburant parcourt, suivant la flèche I I I illustrée sur la figure, la surface 38 jusqu'à atteindre la zone de chasse 32 pour s'y mélanger avec l'air compris en périphérie du cylindre 12.According to the teachings of the invention, the spherical surface 38 of the combustion bowl 24 is shaped so that, after coming into contact with the surface 38 of the inner wall 28, at least a portion of the fuel is wound on itself in swirling movements illustrated in the figure by the arrows I and II and another part of the fuel runs along the arrow III illustrated in FIG. , the surface 38 until reaching the hunting zone 32 to mix with the air included periphery of the cylinder 12.
Avantageusement, les mouvements tourbillonnaires illustrés par les flèches I et I I sont obtenus grâce à la conformation sphérique spécifique de la paroi interne 28 du bol de combustion 24 qui est déterminée pour optimiser le mélange du carburant injecté par l'injecteur ultrasonore 36 avec l'ensemble de l'air présent centralement dans le bol 24.Advantageously, the swirling movements illustrated by the arrows I and II are obtained thanks to the specific spherical conformation of the internal wall 28 of the combustion bowl 24 which is determined to optimize the mixing of the fuel injected by the ultrasonic injector 36 with the assembly. of the air present centrally in the bowl 24.
Selon une variante non représentée, le bol de combustionAccording to a variant not shown, the combustion bowl
24 comporte une paroi interne 28 qui, en coupe axiale, présente un fond 30 plat ou rectiligne qui se raccorde au bord annulaire 26 par un tore présentant un profil curviligne, de préférence globalement circulaire.24 has an inner wall 28 which, in axial section, has a flat or straight bottom 30 which connects to the annular edge 26 by a torus having a curvilinear profile, preferably generally circular.
On décrira maintenant de manière plus détaillée l'injecteur ultrasonore 36 représenté schématiquement sur la figure qui n'est donné qu'à titre d'exemple de réalisation et de manière non limitative.We will now describe in more detail the ultrasonic injector 36 shown schematically in the figure which is given as an exemplary embodiment and without limitation.
L'injecteur ultrasonore 36 comporte principalement, outre l'actuateur 40 et les moyens obturateurs 42, un boîtier 46 présentant une cavité intérieure 48 destinée à être remplie de carburant sous pression par l'intermédiaire d'un perçage axial 49 d'amenée du carburant apte à être relié à un circuit d'alimentation (non représenté).The ultrasonic injector 36 mainly comprises, in addition to the actuator 40 and the shutter means 42, a housing 46 having an internal cavity 48 intended to be filled with pressurized fuel via an axial bore 49 for feeding the fuel adapted to be connected to a power supply circuit (not shown).
Le boîtier 46 comporte à son extrémité inférieure une buse 50 qui est pourvue d'un orifice d'injection 52 du carburant avec lequel communique la cavité intérieure 48.The housing 46 has at its lower end a nozzle 50 which is provided with a fuel injection orifice 52 with which the inner cavity 48 communicates.
Le boîtier 46 comporte au voisinage de la partie supérieure de la buse 50 une partie étagée 54 sur laquelle est de préférence disposée un élément d'appui 56 en matériau amortissant avec lequel coopère une partie de l'actuateur 40.The housing 46 has in the vicinity of the upper part of the nozzle 50 a stepped portion 54 on which is preferably disposed a support member 56 of damping material with which cooperates a portion of the actuator 40.
Avantageusement, l'actuateur 40 de l'injecteur ultrasonoreAdvantageously, the actuator 40 of the ultrasonic injector
36 est formé par un transducteur 58 apte à être commandé pour réaliser sélectivement l'injection de carburant dans la chambre 14 à l'intérieur du bol de combustion 24.36 is formed by a controllable transducer 58 for selectively injecting fuel into the chamber 14 within the combustion bowl 24.
Avantageusement, un tel transducteur 58 constitue un actuateur 40 qui est apte à générer des vibrations dans un mode vertical à des fréquences ultrasonores, de l'ordre de quelques dizaines de kilohertz, par exemple comprises entre 10 et 50 kHz pour permettre des temps d'ouverture minimum de l'ordre deAdvantageously, such a transducer 58 constitutes an actuator 40 which is capable of generating vibrations in a vertical mode at ultrasonic frequencies, of the order of a few tens of kilohertz, for example between 10 and 50 kHz to allow for periods of time. minimum opening of the order of
20μs.20 .mu.s.
De préférence, le transducteur 58 comporte une partie étagée 60 servant d'amplificateur mécanique et se terminant dans sa partie supérieure par un tube 62 dans lequel sont transmises les vibrations provenant du transducteur 58.Preferably, the transducer 58 comprises a stepped portion 60 serving as a mechanical amplifier and ending in its upper part by a tube 62 in which the vibrations coming from the transducer 58 are transmitted.
L'extrémité supérieure du tube 62 comporte une zone de solidarisation avec une tige 64 et à laquelle sont transmises les vibrations axiales selon la direction verticale du transducteur 58. La tige 64 est montée mobile verticalement à l'intérieur de la buse 50 et comporte une extrémité inférieure 66 de forme tronconique destinée à coopérer sélectivement avec un siège complémentaire 68 entourant l'orifice d'injection 52 pour former un clapet apte à constituer des moyens obturateurs 42 selon qu'il occupe une position d'ouverture ou de fermeture.The upper end of the tube 62 comprises a zone of attachment with a rod 64 and to which are transmitted the axial vibrations in the vertical direction of the transducer 58. The rod 64 is mounted vertically movable inside the nozzle 50 and comprises a lower end 66 of frustoconical shape intended to cooperate selectively with a complementary seat 68 surrounding the injection port 52 to form a valve adapted to form shutter means 42 according to whether it occupies an open or closed position.
Avantageusement, l'élément d'appui 56 est apte à exercer une force de rappel élastique tendant à écarter le transducteur 58 de la buse 50 pour rappeler élastiquement l'extrémité tronconiqueAdvantageously, the support element 56 is able to exert an elastic restoring force tending to move the transducer 58 away from the nozzle 50 in order to resiliently return the frustoconical end.
66 de la tige 64 contre le siège 68. De préférence, l'actuateur 40 formé par le transducteur 58 comporte au moins un élément piézoélectrique 70, tel que des céramiques piézo-électriques. En variante, l'actuateur 40 formé par le transducteur 58 comporte au moins un élément électrostatique ou au moins un élément magnétostrictif.66 of the rod 64 against the seat 68. Preferably, the actuator 40 formed by the transducer 58 comprises at least one piezoelectric element 70, such as piezoelectric ceramics. Alternatively, the actuator 40 formed by the transducer 58 comprises at least one electrostatic element or at least one magnetostrictive element.
De tels éléments sont susceptibles de se déformer selon la direction verticale en réponse à l'application d'un champ électrique ou magnétique. Such elements are likely to deform in the vertical direction in response to the application of an electric or magnetic field.

Claims

REVEN D ICATIONS REVEN D ICATIONS
1 . Moteur (10) à combustion interne à injection directe, notamment pour véhicule automobile, comportant au moins un cylindre (12) et une chambre de combustion (14) qui est délimitée axialement, dans sa partie supérieure, par une face inférieure (16) d'une culasse (18) du moteur (10) et, dans sa partie inférieure, par une face supérieure (20) d'un piston (22) d'axe vertical (X-X) qui coulisse alternativement dans le cylindre (12), dans lequel le piston (22) comporte un bol de combustion (24) qui est délimité par un bord annulaire (26) dans la face supérieure (20) du piston (22) et par une paroi interne (28) qui s'étend depuis ce bord (26) jusqu'à un fond (30), ledit bord annulaire (26) formant avec la face supérieure (20) du piston (22) une zone de chasse (32), dans lequel la culasse (18) porte au moins un dispositif d'injection (34) apte à injecter le carburant vers le bol de combustion (24), caractérisé en ce que le dispositif d'injection (34) comporte au moins un injecteur (36) ultrasonore comportant un actuateur (40) apte à commander à fréquence d'excitation ultrasonore sélectivement des moyens obturateurs (42) pour injecter le carburant sous la forme d'une nappe d'injection (44) sensiblement conique présentant un faible angle d'ouverture (α) et en ce que le bol de combustion (24) associé à l'injecteur ultrasonore (36) comporte une paroi interne (28) formée par une surface concave (38) globalement sphérique. 1. Direct injection internal combustion engine (10), in particular for a motor vehicle, comprising at least one cylinder (12) and a combustion chamber (14) which is delimited axially, in its upper part, by a lower face (16) of a cylinder head (18) of the engine (10) and, in its lower part, by an upper face (20) of a piston (22) of vertical axis (XX) which slides alternately in the cylinder (12), in wherein the piston (22) comprises a combustion bowl (24) which is delimited by an annular edge (26) in the upper face (20) of the piston (22) and by an inner wall (28) which extends therethrough edge (26) to a bottom (30), said annular edge (26) forming with the upper face (20) of the piston (22) a flushing zone (32), wherein the yoke (18) carries at least an injection device (34) adapted to inject the fuel to the combustion bowl (24), characterized in that the injection device (34) comprises at least one injection ultrasound transducer (36) comprising an actuator (40) capable of selectively controlling, at an ultrasonic excitation frequency, shutter means (42) for injecting the fuel in the form of a substantially conical injection ply (44) having a low angle opening (α) and in that the combustion bowl (24) associated with the ultrasonic injector (36) has an inner wall (28) formed by a concave surface (38) globally spherical.
2. Moteur selon la revendication 1 , caractérisé en ce que le bol de combustion (24) comporte une paroi interne (28, 38) qui, en coupe axiale, présente un profil circulaire.2. Engine according to claim 1, characterized in that the combustion bowl (24) has an inner wall (28, 38) which, in axial section, has a circular profile.
3. Moteur selon la revendication 1 , caractérisé en ce que le bol de combustion (24) comporte une paroi interne (28, 38) qui, en coupe axiale, présente un fond (30) plat qui se raccorde au bord annulaire (26) par une portion présentant un profil curviligne.3. Engine according to claim 1, characterized in that the combustion bowl (24) has an inner wall (28, 38) which, in axial section, has a bottom (30) flat which connects to the annular edge (26). by a portion having a curvilinear profile.
4. Moteur selon l'une quelconque des revendications 1 à 3, caractérisé en ce que l'angle (α) de la nappe d'injection (44) déterminé par l'intersection d'un axe moyen (A) d'injection de la nappe d'injection et de l'axe (X-X) du piston (22) est un angle, dit fermé, dont la valeur est comprise entre 20° et 45° de manière à favoriser la pénétration du carburant de la nappe (44) dans le bol de combustion (24).4. Motor according to any one of claims 1 to 3, characterized in that the angle (α) of the injection ply (44) determined by the intersection of a mean axis (A) of injection of the injection ply and the axis (XX) of the piston (22) is an angle, said closed, whose value is between 20 ° and 45 ° so as to promote the penetration of fuel from the web (44) into the combustion bowl (24).
5. Moteur selon l'une quelconque des revendications précédentes, caractérisé en ce que le moteur (10) est du type à allumage par compression .5. Motor according to any one of the preceding claims, characterized in that the motor (10) is of the compression ignition type.
6. Moteur selon l'une quelconque des revendications précédentes, caractérisé en ce que la surface globalement sphérique (38) formant la paroi interne (28) du bol de combustion (24) est conformée avec une concavité déterminée de manière que, après leur entrée en contact avec la surface (38), au moins une partie du carburant s'enroule sur lui-même suivant des mouvements tourbillonnaires (I , I I ) aptes à optimiser le mélange du carburant avec l'air présent centralement dans le bol (24) et qu'une autre partie du carburant (I I I ) parcourt la surface (38) jusqu'à atteindre la zone de chasse (32) pour s'y mélanger avec l'air compris en périphérie du cylindre (12). 6. Motor according to any one of the preceding claims, characterized in that the generally spherical surface (38) forming the inner wall (28) of the combustion bowl (24) is shaped with a concavity determined so that, after their entry in contact with the surface (38), at least a portion of the fuel rolls up on itself in swirling motions (I, II) able to optimize the mixing of the fuel with the air present centrally in the bowl (24) and that another portion of the fuel (III) travels the surface (38) to reach the flush zone (32) to mix with the air included at the periphery of the cylinder (12).
7. Moteur selon l'une quelconque des revendications précédentes, caractérisé en ce que le bol de combustion (24) est centré par rapport au sommet de la nappe d'injection (44) et en ce que l'injecteur ultrasonore (36) est centré sur l'axe (X-X) du piston (22). 7. Motor according to any one of the preceding claims, characterized in that the combustion bowl (24) is centered with respect to the top of the injection ply (44) and in that the ultrasonic injector (36) is centered on the axis (XX) of the piston (22).
8. Moteur selon l'une quelconque des revendications précédentes, caractérisé en que l'actuateur (40) de l'injecteur ultrasonore (36) est formé par un transducteur (58) apte à être commandé pour réaliser sélectivement l'injection de carburant dans le bol de combustion (24) de la chambre de combustion (24). 8. Motor according to any one of the preceding claims, characterized in that the actuator (40) of the ultrasonic injector (36) is formed by a transducer (58) capable of being controlled to selectively perform fuel injection in the combustion bowl (24) of the combustion chamber (24).
9. Moteur selon la revendication 8, caractérisé en que l'actuateur (40, 58) comporte au moins un élément piézoélectrique (70), tel que des céramiques piézo-électriques. 9. Motor according to claim 8, characterized in that the actuator (40, 58) comprises at least one piezoelectric element (70), such as piezoelectric ceramics.
10. Moteur selon la revendication 8, caractérisé en que l'actuateur (40, 58) comporte au moins un élément électrostatique ou au moins un élément magnétostrictif. 10. Motor according to claim 8, characterized in that the actuator (40, 58) comprises at least one electrostatic element or at least one magnetostrictive element.
PCT/FR2009/050158 2008-02-06 2009-02-03 Internal combustion engine comprising a combustion bowl for an injector of the ultrasonic type WO2009101318A1 (en)

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FR0850745A FR2927120B1 (en) 2008-02-06 2008-02-06 INTERNAL COMBUSTION ENGINE COMPRISING A COMBUSTION BOWL FOR AN ULTRASOUND TYPE INJECTOR
FR0850745 2008-02-06

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JPS5726222A (en) * 1980-07-25 1982-02-12 Nissan Motor Co Ltd Internal combustion engine in which fuel is injected into cylinder
JPS58204967A (en) * 1982-05-26 1983-11-29 Hitachi Ltd Cylinder injection engine
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* Cited by examiner, † Cited by third party
Publication number Priority date Publication date Assignee Title
US20130068200A1 (en) * 2011-09-15 2013-03-21 Paul Reynolds Injector Valve with Miniscule Actuator Displacement
US20150285198A1 (en) * 2011-09-15 2015-10-08 Weidlinger Associates, Inc. Injector Valve with Miniscule Actuator Displacement

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FR2927120B1 (en) 2010-02-12

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