WO2009101341A1 - Internal combustion engine comprising a double‑cavity combustion bowl for an ultrasonic injector - Google Patents

Internal combustion engine comprising a double‑cavity combustion bowl for an ultrasonic injector Download PDF

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Publication number
WO2009101341A1
WO2009101341A1 PCT/FR2009/050188 FR2009050188W WO2009101341A1 WO 2009101341 A1 WO2009101341 A1 WO 2009101341A1 FR 2009050188 W FR2009050188 W FR 2009050188W WO 2009101341 A1 WO2009101341 A1 WO 2009101341A1
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WO
WIPO (PCT)
Prior art keywords
cavity
injection
fuel
combustion bowl
piston
Prior art date
Application number
PCT/FR2009/050188
Other languages
French (fr)
Inventor
Magali Besson
Lysiane Grosjean
Fabien Defransure
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 WO2009101341A1 publication Critical patent/WO2009101341A1/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
    • 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
    • F02B23/0678—Unconventional, complex or non-rotationally symmetrical shapes of the combustion space, e.g. flower like, having special shapes related to the orientation of the fuel spray jets
    • F02B23/0684—Ring like bowl, e.g. toroidal
    • 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
    • F02B23/0678—Unconventional, complex or non-rotationally symmetrical shapes of the combustion space, e.g. flower like, having special shapes related to the orientation of the fuel spray jets
    • F02B23/0687—Multiple bowls in the piston, e.g. one bowl per fuel spray jet
    • 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 having a dual-cavity combustion bowl for an ultrasonic injector.
  • the invention more particularly relates to an internal combustion engine with indirect injection, in particular for a motor vehicle, comprising at least one cylindrical cylinder and a combustion chamber which is delimited axially, in its upper part, by a lower surface of a cylinder head of the engine and, in its lower part, by an upper face of a piston of vertical axis which is cast alternately in the cylinder lash, in which the piston comprises a combustion bowl which i is delimited by a annular rim in the upper face of the piston and by an inner wall that extends from this edge to a bottom, led it annular edge forming with the upper face of the piston a hunting zone, wherein the breech carries at least an injection device suitable for injecting the fuel into the combustion bowl.
  • 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 suitable for optimizing the operation of the engine, in particular a reduction in fuel consumption as well as 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 jet jets.
  • the shutter means are for example constituted by a needle or a needle and are controlled to achieve the injection, the fuel being sprayed in the form of jet jets via holes d isposés to the lower end of 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 scale that are complementary to the jets determining an injection ply having a large opening angle that , determined by the intersection of a jet and the vertical axis XX of the piston, is for example greater than 60 °.
  • Such a combustion bowl is still geometrically characterized by a shallow depth and the presence of a central boss that 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. Following a first path, a portion of the fuel jet rises vertically above the impact zone with the inner wall of the combustion bowl so that this portion of the fuel is directed to the hunting zone and the upper face of the piston. Following a second path, the other part of the fuel rolls up along the inner wall of the outer torus of the combustion bowl and then travels towards the center of the bowl having the central boss from which it traverses the generally frustoconical external surface for move vertically towards the cylinder head carrying the injector.
  • Document EP-A-1 72552 describes an example of an ultrasonic-type fuel injector suitable for injecting the fuel in the form of an injection ply and not of jets of iscrets.
  • 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 the fuel into a bowl of this type is insufficient and therefore the operation of the intake air is not optimal, which leads to a quality of mixing that is degraded compared to a engine having a jet fuel injector.
  • the penetration of fuel injected by an ultrasonic injector is effected with a lesser amount of movement, that is to say an upper fuel mass injected at a lower speed, so that the winding of fuel in the toroidal portion of the combustion bowl according to the second chem in the above does not occur or little.
  • the air present in the combustion bowl is therefore poorly or little exploited and the mixture of the intake air and the fuel is mainly due to the aspiration of the fuel by the hunting zone according to the first chem in the aforementioned.
  • the phenomenon of flushing effect occurring only in determined conditions, in particular more or less 30 ° degree around the high engine point or PMH compared to the crankshaft, it is insufficient to obtain a qual ity of mixing satisfactory to improve the performance of the engine while reducing em issions of pollutants.
  • the object of the invention is therefore in particular to solve these drawbacks and to propose an internal combustion engine comprising a combustion chamber that can be used 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 injector of the ultrasonic type and in that the combustion bowl associated with the injector ultrasonore comprises respectively a first concave cavity that i, arranged centrally, forms a main chamber and a second annular cavity that i, surrounding the first cavity, forms an auxiliary chamber.
  • 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 combination of the dual-cavity combustion bowl with an ultrasonic injector, the operation of the air contained on the one hand in the first cavity of the mixing bowl is optimized.
  • the fuel following vortex movements caused by the interaction between the fuel ply and the globally spherical inner wall of the first cavity and secondly in the second cavity forming a "reserve" of air.
  • the mixture of air and fuel is thus obtained via a first course of the fuel following the aforementioned swirling movements and a second course corresponding to the portion of the fuel sucked towards the hunting zone, suction is amplified by the presence of the second cavity.
  • the first cavity of the combustion bowl comprises a spherical inner wall which, in axial section, has a generally curvilinear profile, such as a circular arc;
  • the second cavity of the combustion bowl has an inner wall which, in axial section, has a curvil igne profile; the inner wall of the second cavity, extending vertically from the bottom of the side of the first cavity, presents in axial section a frustoconical profile; the ultrasonic injector is capable of injecting the fuel in the form of a substantially conical injection ply having a small opening angle which, determined by the intersection of a mean axis of injection of the plywood, injection and the piston pin, has a value between 20 ° 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 first cavity of the combustion bowl is centered with respect to the top of the injection ply and the ultrasonic injector is centered on the axis of the plunger;
  • the ultrasonic injector comprises an actuator able to selectively control shutter means for injecting the fuel, and the actuator is formed by a transducer that can be controlled to selectively perform the injection of fuel into the combustion bowl of the fuel chamber; combustion; 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.
  • FIG. 1 is a schematic view in axial section showing a combustion chamber of an internal combustion engine equipped with an ultrasonic type injector.
  • 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.
  • the annular edge 26 forms, with the upper face 20 of the piston 22, a hunting zone 28.
  • the yoke 18 of the engine 10 carries at least one injection device 30 comprising at least one injector capable of injecting the fuel towards the combustion bowl 24.
  • the injection device 30 consisting of at least one injector 32 of the ultrasonic type and the combustion bowl 24 associated with the ultrasonic injector 32 respectively comprises a first concave cavity 34 which, arranged centrally, forms a chamber main and a second annular cavity 36 which, surrounding the first cavity, forms an auxiliary chamber.
  • the first cavity 34 of the combustion bowl 24 has an inner wall 38 of spherical shape which, in axial section, has a generally curvilinear profile, such as a circular arc.
  • the inner wall 38 of the first cavity 34 has in axial section a circular profile.
  • the inner wall 38 of the first cavity 34 has in axial section a generally circular profile with a bottom 35 substantially flat or rectil igne.
  • the second cavity 36 of the combustion bowl 24 has an inner wall 37 which, in axial section, has a curvil igne profile.
  • the inner wall 37 of the second cavity 36 extends vertically on either side of a bottom 39, the radially internal portion of the inner wall 37 isposed on the side of the first cavity 34 advantageously having, in axial section, a frustoconical profile as illustrated in the figure.
  • the injection ply 44 is constituted, as in EP-B1-1.1 72.552, by a cloud of fuel drops whose sizes are very similar and sufficiently small.
  • the ultrasonic injector 32 comprises at least one actuator
  • 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 closed angle, the value of which is advantageously between 20 ° and 50 ° in order to promote the penetration of the fuel from the ply 44 into the first cavity 34. of the combustion bowl 24 by optimizing the operation made of the momentum of the fuel.
  • the first and second cavities 34, 36 of the combustion bowl 24 are centered with respect to the top of the injection ply 44.
  • the ultrasound injector 32 is here centered on the vertical axis XX of the piston 22 and thus centered with respect to the first cavity 34 of the combustion bowl 24.
  • a double-cavity combustion bowl 24 is a shape that can be obtained by simple and inexpensive machining operations.
  • the spherical wall 38 of the first cavity 34 is shaped with a concavity determined according to the parameters of the injection ply 44 of the associated ultrasonic injector 32.
  • the spherical wall 38 of the combustion bowl 24 is shaped so that, after coming into contact with the surface of the inner wall 38, at least a portion of the fuel is wound on itself following vortex movements illustrated in the figure by the arrows I and II and another part of the fuel travels, according to the arrow I II illustrated in the figure, the surface 38 to reach the hunting zone 28 for there mixing with the air included in the second cavity 36 arranged at the 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 inner wall 38 of the central cavity 34 of the combustion bowl 24 which is determined to optimize mixing of the fuel injected by the ultrasonic injector. 32 with all the air present centrally in the bowl 24.
  • the ultrasonic injector 32 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 supplying fuel capable of being relied on an feed circuit (not shown).
  • the housing 46 has at its lower end a nozzle 50 which is provided with an injection port 52 of the fuel with which the inner cavity 48 communicates.
  • the housing 46 comprises, in the vicinity of the upper part of the nozzle 50, a stepped portion 54 on which is preferably disposed a support element 56 of damping material with which a part of the actuator 40 cooperates.
  • controllable transducer 58 for selectively injecting fuel into the chamber 14 within the first cavity 34 of the combustion bowl 24.
  • such a transducer 58 constitutes an actuator 40 that 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 enable minimum opening time of the order of 20 ⁇ s.
  • the transducer 58 comprises a stepped portion 60 serving as a mechanical amplifier and terminating 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 an idarization ground zone with a rod 64 and to which the axial vibrations are transmitted in the vertical direction of the transducer 58.
  • the rod 64 is mounted vertically movable inside the nozzle 50 and has a frustoconical lower end 66 designed to cooperate selectively with a complementary seat 68 surrounding the injection orifice 52 to form a valve adapted to constitute means shutters 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 to resiliently return the frustoconical end 66 of the rod 64 against the seat 68.
  • 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)
  • Dispersion Chemistry (AREA)
  • Chemical Kinetics & Catalysis (AREA)
  • Fuel-Injection Apparatus (AREA)

Abstract

The invention relates to a direct‑injection internal combustion engine (10), characterized in that it comprises an injection device (30) of the engine (10) comprising at least one ultrasonic injector (32) able to inject fuel into a combustion chamber (14) delimited axially in its lower part by a combustion bowl (24) created in an upper face (20) of a piston (22), and in that the combustion bowl (24) associated with the ultrasonic injector (32) respectively comprises a concave first cavity (34) which, arranged centrally, forms a main chamber, and a second cavity (36) which, surrounding the first cavity, forms an auxiliary chamber.

Description

"Moteur à combustion interne comportant un bol de combustion à double cavité pour un injecteur ultrasonore" "Internal combustion engine having a dual cavity combustion bowl for an ultrasonic injector"
L'invention concerne un moteur à combustion interne comportant un bol de combustion à double cavité pour un injecteur ultrasonore.The invention relates to an internal combustion engine having a dual-cavity combustion bowl for an ultrasonic injector.
L'invention concerne plus particul ièrement un moteur à combustion interne à injection d irecte, notamment pour véhicule automobile, comportant au moins un cyl indre et une chambre de combustion qu i est dél imitée axialement, dans sa partie supérieure, par une face inférieure d'une culasse du moteur et, dans sa partie inférieure, par une face supérieure d'un piston d'axe vertical qu i coul isse alternativement dans le cyl indre, dans lequel le piston comporte un bol de combustion qu i est dél imité par un bord annulaire dans la face supérieure du piston et par une paroi interne qu i s'étend depuis ce bord jusqu'à un fond, led it bord annulaire formant avec la face supérieure du piston une zone de chasse, dans lequel la culasse porte au moins un d ispositif 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 particul ièrement un bol de combustion dans le piston qui est conformée en fonction du dispositif d'injection du moteur auquel il est associé.The invention more particularly relates to an internal combustion engine with indirect injection, in particular for a motor vehicle, comprising at least one cylindrical cylinder and a combustion chamber which is delimited axially, in its upper part, by a lower surface of a cylinder head of the engine and, in its lower part, by an upper face of a piston of vertical axis which is cast alternately in the cylinder indre, in which the piston comprises a combustion bowl which i is delimited by a annular rim in the upper face of the piston and by an inner wall that extends from this edge to a bottom, led it annular edge forming with the upper face of the piston a hunting zone, wherein the breech carries at least an injection device suitable for injecting the fuel into the combustion bowl. 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 déterm inée en fonction des caractéristiques du d ispositif d'injection de manière à obten ir 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 suitable for optimizing the operation of the engine, in particular a reduction in fuel consumption as well as 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 d iscrets. Dans un tel injecteur, les moyens obturateurs sont par exemple constitués par un pointeau ou une aigu ille et sont commandés pour réal iser l'injection, le carburant étant pulvérisé sous la forme de jets d iscrets par l'interméd iaire de trous d isposés 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 jet jets. In such an injector, the shutter means are for example constituted by a needle or a needle and are controlled to achieve the injection, the fuel being sprayed in the form of jet jets via holes d isposés to the lower end of 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 d iamètre important qu i sont complémentaires des jets déterminant une nappe d'injection présentant un grand angle d'ouverture qu i, déterm iné 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 scale that are complementary to the jets determining an injection ply having a large opening angle that , determined by the intersection of a jet and the vertical axis XX of the piston, is for example greater than 60 °.
Un tel bol de combustion se caractérise encore géométriquement par une faible profondeur et la présence d'un bossage central qu i 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 that 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 . Su ivant un prem ier 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 d irigée vers la zone de chasse et la face supérieure du piston . Su ivant un deuxième chemin , l'autre partie du carburant s'enroule en suivant la paroi interne du tore extérieur du bol de combustion puis se d irige vers le centre du bol comportant le bossage central dont il parcourt la surface externe globalement troncon ique pour se d iriger 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. Following a first path, a portion of the fuel jet rises vertically above the impact zone with the inner wall of the combustion bowl so that this portion of the fuel is directed to the hunting zone and the upper face of the piston. Following a second path, the other part of the fuel rolls up along the inner wall of the outer torus of the combustion bowl and then travels towards the center of the bowl having the central boss from which it traverses the generally frustoconical external surface for move vertically towards the cylinder head carrying the injector.
Le document EP-A-1 .1 72.552 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 d iscrets. 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. Avec un tel injecteur ultrasonore, la pénétration du carburant dans un bol de ce type est insuffisante et par conséquent l'exploitation de l'air d'admission n'est pas optimale ce qui conduit à une qual ité de mélange dégradée par rapport à un moteur comportant un injecteur de carburant à jets d iscrets. En effet, la pénétration du carburant injecté par un injecteur ultrasonore s'effectue avec une moindre quantité de mouvement, c'est-à-d ire 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 chem in précité ne se produit pas ou peu .Document EP-A-1 72552 describes an example of an ultrasonic-type fuel injector suitable for injecting the fuel in the form of an injection ply and not of jets of iscrets. 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. With such an ultrasonic injector, the penetration of the fuel into a bowl of this type is insufficient and therefore the operation of the intake air is not optimal, which leads to a quality of mixing that is degraded compared to a engine having a jet fuel injector. Indeed, the penetration of fuel injected by an ultrasonic injector is effected with a lesser amount of movement, that is to say an upper fuel mass injected at a lower speed, so that the winding of fuel in the toroidal portion of the combustion bowl according to the second chem in the above 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 chem in précité. Toutefois, le phénomène d'effet de chasse ne se produ isant que dans des cond itions déterm inées, notamment plus ou moins 30° degré autour du point moteur haut ou PMH par rapport au vilebrequin , il est insuffisant pour obtenir une qual ité de mélange satisfaisante propre à amél iorer les performances du moteur tout en rédu isant les ém issions de polluants.The air present in the combustion bowl is therefore poorly or little exploited and the mixture of the intake air and the fuel is mainly due to the aspiration of the fuel by the hunting zone according to the first chem in the aforementioned. However, the phenomenon of flushing effect occurring only in determined conditions, in particular more or less 30 ° degree around the high engine point or PMH compared to the crankshaft, it is insufficient to obtain a qual ity of mixing satisfactory to improve the performance of the engine while reducing em issions of pollutants.
L'invention a donc notamment pour but de résoudre ces inconvén ients 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 d ispositif d'injection comporte au moins un injecteur du type ultrasonore et en ce que le bol de combustion associé à l'injecteur ultrasonore comporte respectivement une première cavité concave qu i, agencée centralement, forme une chambre principale et une deuxième cavité annulaire qu i, entourant la prem ière cavité, forme une chambre auxiliaire. 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 optim isant la répartition spatiale de la quantité de mouvement. Grâce à la combinaison selon l'invention caractérisée par l'association du bol de combustion à double cavité avec un injecteur ultrasonore, on optim ise l'exploitation de l'air contenu d'une part dans la première cavité du bol qui se mélange avec le carburant su ivant des mouvements tourbillonnaires provoqués par l'interaction entre la nappe de carburant et la paroi interne globalement sphérique de la prem ière cavité et, d'autre part, dans la deuxième cavité formant une "réserve" d'air.The object of the invention is therefore in particular to solve these drawbacks and to propose an internal combustion engine comprising a combustion chamber that can be used 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 injector of the ultrasonic type and in that the combustion bowl associated with the injector ultrasonore comprises respectively a first concave cavity that i, arranged centrally, forms a main chamber and a second annular cavity that i, surrounding the first cavity, forms an auxiliary chamber. 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. . Thanks to the combination according to the invention characterized by the combination of the dual-cavity combustion bowl with an ultrasonic injector, the operation of the air contained on the one hand in the first cavity of the mixing bowl is optimized. the fuel following vortex movements caused by the interaction between the fuel ply and the globally spherical inner wall of the first cavity and secondly in the second cavity forming a "reserve" of air.
Avantageusement, le mélange de l'air et du carburant est donc obtenu par l'intermédiaire d'un premier parcours du carburant suivant les mouvements tourbillonnaires précités et d'un second parcours correspondant à la partie du carburant aspirée vers la zone de chasse, l'aspiration étant ampl ifiée par la présence de la deuxième cavité.Advantageously, the mixture of air and fuel is thus obtained via a first course of the fuel following the aforementioned swirling movements and a second course corresponding to the portion of the fuel sucked towards the hunting zone, suction is amplified by the presence of the second cavity.
Selon d'autres caractéristiques de l'invention : - la première cavité du bol de combustion comporte une paroi interne sphérique qui, en coupe axiale, présente un profil globalement curvil igne, tel qu'un arc de cercle ;According to other characteristics of the invention: the first cavity of the combustion bowl comprises a spherical inner wall which, in axial section, has a generally curvilinear profile, such as a circular arc;
- la deuxième cavité du bol de combustion comporte une paroi interne qui, en coupe axiale, présente un profil curvil igne ; - la paroi interne de la deuxième cavité, s'étendant verticalement à partir du fond du côté de la première cavité, présente en coupe axiale un profil troncon ique ; - l'injecteur ultrasonore est apte à injecter le carburant sous la forme d'une nappe d'injection sensiblement con ique présentant un faible angle d'ouverture qui, déterminé par l'intersection d'un axe moyen d'injection de la nappe d'injection et de l'axe du piston , a une valeur comprise entre 20° et 50° de man ière à favoriser la pénétration du carburant de la nappe dans le bol de combustion .- The second cavity of the combustion bowl has an inner wall which, in axial section, has a curvil igne profile; the inner wall of the second cavity, extending vertically from the bottom of the side of the first cavity, presents in axial section a frustoconical profile; the ultrasonic injector is capable of injecting the fuel in the form of a substantially conical injection ply having a small opening angle which, determined by the intersection of a mean axis of injection of the plywood, injection and the piston pin, has a value between 20 ° and 50 ° so as to promote the penetration of fuel from the web into the combustion bowl.
- le moteur est du type à allumage par compression ;the engine is of the compression ignition type;
- la première cavité du bol de combustion est centrée par rapport au sommet de la nappe d'injection et l'injecteur ultrasonore est centré sur l'axe du piston ;the first cavity of the combustion bowl is centered with respect to the top of the injection ply and the ultrasonic injector is centered on the axis of the plunger;
- l'injecteur ultrasonore comporte un actuateur apte à commander sélectivement des moyens obturateurs pour injecter le carburant et l'actuateur est formé par un transducteur apte à être commandé pour réal iser 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.the ultrasonic injector comprises an actuator able to selectively control shutter means for injecting the fuel, and the actuator is formed by a transducer that can be controlled to selectively perform the injection of fuel into the combustion bowl of the fuel chamber; combustion; the actuator comprises at least one piezoelectric element, such as piezoelectric ceramics.
- l'actuateur comporte au moins un élément électrostatique ou au moins un élément magnétostrictif.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 qu i su it pour la compréhension de laquelle on se reportera à la figure un ique annexée. 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.Other features and advantages of the invention will become apparent from reading the detailed description which is provided for the understanding of which reference will be made to the attached FIG. 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 qu i va suivre et les revend ications, on util isera à titre non l imitatif les termes, tels que "supérieure" et "inférieure", "axial" et "radial" et les orientations "longitud inale", "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. 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.In the description which will be followed and the claims, the terms such as "upper" and "lower", "axial" and "radial" and the "longitudinal", "vertical" orientations will be used as non-imitative. "and" transverse "to respectively designate elements according to the definitions given in the description and with respect to the trihedron (L, V, T) shown in the figure. 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 en 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.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.
Le bord annulaire 26 forme, avec la face supérieure 20 du piston 22, une zone de chasse 28.The annular edge 26 forms, with the upper face 20 of the piston 22, a hunting zone 28.
La culasse 18 du moteur 10 porte au moins un dispositif d'injection 30 comportant au moins un injecteur apte à injecter le carburant vers le bol de combustion 24.The yoke 18 of the engine 10 carries at least one injection device 30 comprising at least one injector capable of injecting the fuel towards the combustion bowl 24.
Conformément à l'invention, le dispositif d'injection 30 constitué par au moins un injecteur 32 du type ultrasonore et le bol de combustion 24 associé à l'injecteur ultrasonore 32 comporte respectivement une première cavité 34 concave qui, agencée centralement, forme une chambre principale et une deuxième cavité 36 annulaire qui, entourant la première cavité, forme une chambre auxiliaire.According to the invention, the injection device 30 consisting of at least one injector 32 of the ultrasonic type and the combustion bowl 24 associated with the ultrasonic injector 32 respectively comprises a first concave cavity 34 which, arranged centrally, forms a chamber main and a second annular cavity 36 which, surrounding the first cavity, forms an auxiliary chamber.
La première cavité 34 du bol de combustion 24 comporte une paroi interne 38 de forme sphérique qui, en coupe axiale, présente un profil globalement curviligne, tel qu'un arc de cercle.The first cavity 34 of the combustion bowl 24 has an inner wall 38 of spherical shape which, in axial section, has a generally curvilinear profile, such as a circular arc.
Avantageusement, la paroi interne 38 de la première cavité 34 présente en coupe axiale un profil circulaire. En variante non représentée, la paroi interne 38 de la première cavité 34 présente en coupe axiale un profil globalement circulaire avec un fond 35 sensiblement plat ou rectil igne.Advantageously, the inner wall 38 of the first cavity 34 has in axial section a circular profile. In variant not shown, the inner wall 38 of the first cavity 34 has in axial section a generally circular profile with a bottom 35 substantially flat or rectil igne.
Avantageusement, la deuxième cavité 36 du bol de combustion 24 comporte une paroi interne 37 qui, en coupe axiale, présente un profil curvil igne.Advantageously, the second cavity 36 of the combustion bowl 24 has an inner wall 37 which, in axial section, has a curvil igne profile.
De préférence, la paroi interne 37 de la deuxième cavité 36 s'étend verticalement de part et d'autre d'un fond 39, la partie rad ialement interne de la paroi interne 37 d isposée du côté de la première cavité 34 présentant avantageusement, en coupe axiale, un profil troncon ique comme illustré sur la figure.Preferably, the inner wall 37 of the second cavity 36 extends vertically on either side of a bottom 39, the radially internal portion of the inner wall 37 isposed on the side of the first cavity 34 advantageously having, in axial section, a frustoconical profile as illustrated in the figure.
La nappe d'injection 44 est constituée comme dans le brevet EP-B1 -1 .1 72.552 d'un nuage de gouttes de carburant dont les tailles sont très voisines et suffisamment petites. L'injecteur ultrasonore 32 comporte au moins un actuateurThe injection ply 44 is constituted, as in EP-B1-1.1 72.552, by a cloud of fuel drops whose sizes are very similar and sufficiently small. The ultrasonic injector 32 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" . 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 22.40 able to control at selectively ultrasonic excitation frequency shutter means 42 for injecting the fuel in the form of a substantially conical injection web 44 having a small opening angle "α". 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, d it fermé, dont la valeur est avantageusement comprise entre 20° et 50° de man ière à favoriser la pénétration du carburant de la nappe 44 dans la prem ière cavité 34 du 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 closed angle, the value of which is advantageously between 20 ° and 50 ° in order to promote the penetration of the fuel from the ply 44 into the first cavity 34. of the combustion bowl 24 by optimizing the operation made of the momentum of the fuel.
De préférence, les prem ière et deuxième cavités 34, 36 du bol de combustion 24 sont centrées par rapport au sommet de la nappe d'injection 44.Preferably, the first and second cavities 34, 36 of the combustion bowl 24 are centered with respect to the top of the injection ply 44.
Avantageusement, l'injecteur ultrasonore 32 est ici centré sur l'axe vertical X-X du piston 22 et donc centré par rapport à la première cavité 34 du bol de combustion 24. Avantageusement, un tel bol de combustion 24 à double cavité est une forme susceptible d'être obtenue par des opérations d'usinage simples et peu coûteuses.Advantageously, the ultrasound injector 32 is here centered on the vertical axis XX of the piston 22 and thus centered with respect to the first cavity 34 of the combustion bowl 24. Advantageously, such a double-cavity combustion bowl 24 is a shape that can be obtained by simple and inexpensive machining operations.
Avantageusement, la paroi sphérique 38 de la première cavité 34 est conformée avec une concavité déterminée en fonction des paramètres de la nappe d'injection 44 de l'injecteur ultrasonore 32 associé.Advantageously, the spherical wall 38 of the first cavity 34 is shaped with a concavity determined according to the parameters of the injection ply 44 of the associated ultrasonic injector 32.
Conformément aux enseignements de l'invention, la paroi sphérique 38 du bol de combustion 24 est conformée de manière que, après leur entrée en contact avec la surface de la paroi interne 38, 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 II illustrée sur la figure, la surface 38 jusqu'à atteindre la zone de chasse 28 pour s'y mélanger avec l'air compris dans la deuxième cavité 36 agencée en périphérie du cylindre 12.According to the teachings of the invention, the spherical wall 38 of the combustion bowl 24 is shaped so that, after coming into contact with the surface of the inner wall 38, at least a portion of the fuel is wound on itself following vortex movements illustrated in the figure by the arrows I and II and another part of the fuel travels, according to the arrow I II illustrated in the figure, the surface 38 to reach the hunting zone 28 for there mixing with the air included in the second cavity 36 arranged at the periphery of the cylinder 12.
Avantageusement, les mouvements tourbillonnaires illustrés par les flèches I et II sont obtenus grâce à la conformation sphérique spécifique de la paroi interne 38 de la cavité centrale 34 du bol de combustion 24 qui est déterminée pour optimiser le mélange du carburant injecté par l'injecteur ultrasonore 32 avec l'ensemble de l'air présent centralement dans le bol 24. On décrira maintenant de man ière plus détaillée l'injecteur ultrasonore 32 représenté schématiquement sur la figure qui n'est donné qu'à titre d'exemple de réalisation et de manière non limitative.Advantageously, the swirling movements illustrated by the arrows I and II are obtained thanks to the specific spherical conformation of the inner wall 38 of the central cavity 34 of the combustion bowl 24 which is determined to optimize mixing of the fuel injected by the ultrasonic injector. 32 with all the air present centrally in the bowl 24. The ultrasonic injector 32 shown schematically in the figure which is given only as an example embodiment and non-restrictive way.
L'injecteur ultrasonore 32 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 rel ié à un circuit d'al imentation (non représenté).The ultrasonic injector 32 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 supplying fuel capable of being relied on an feed circuit (not shown).
Le boîtier 46 comporte à son extrém ité inférieure une buse 50 qu i est pourvue d'un orifice d'injection 52 du carburant avec lequel commun ique la cavité intérieure 48.The housing 46 has at its lower end a nozzle 50 which is provided with an injection port 52 of the fuel 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 d isposée un élément d'appui 56 en matériau amortissant avec lequel coopère une partie de l'actuateur 40. Avantageusement, l'actuateur 40 de l'injecteur ultrasonoreThe housing 46 comprises, in the vicinity of the upper part of the nozzle 50, a stepped portion 54 on which is preferably disposed a support element 56 of damping material with which a part of the actuator 40 cooperates. Advantageously, 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 de la première cavité 34 du bol de combustion 24.36 is formed by a controllable transducer 58 for selectively injecting fuel into the chamber 14 within the first cavity 34 of the combustion bowl 24.
Avantageusement, un tel transducteur 58 constitue un actuateur 40 qu i est apte à générer des vibrations dans un mode vertical à des fréquences ultrasonores, de l'ordre de quelques d izaines de kilohertz, par exemple comprises entre 1 0 et 50 kHz pour permettre des temps d'ouverture minimum de l'ordre de 20μs. De préférence, le transducteur 58 comporte une partie étagée 60 servant d'ampl ificateur mécan ique et se terminant dans sa partie supérieure par un tube 62 dans lequel sont transmises les vibrations provenant du transducteur 58.Advantageously, such a transducer 58 constitutes an actuator 40 that 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 enable minimum opening time of the order of 20μs. Preferably, the transducer 58 comprises a stepped portion 60 serving as a mechanical amplifier and terminating in its upper part by a tube 62 in which the vibrations coming from the transducer 58 are transmitted.
L'extrém ité supérieure du tube 62 comporte une zone de sol idarisation avec une tige 64 et à laquelle sont transmises les vibrations axiales selon la direction verticale du transducteur 58.The upper end of the tube 62 comprises an idarization ground zone with a rod 64 and to which the axial vibrations are transmitted in the vertical direction of the transducer 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. 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 tronconique 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.The rod 64 is mounted vertically movable inside the nozzle 50 and has a frustoconical lower end 66 designed to cooperate selectively with a complementary seat 68 surrounding the injection orifice 52 to form a valve adapted to constitute means shutters 42 according to whether it occupies an open or closed position. Advantageously, the support element 56 is able to exert an elastic restoring force tending to move the transducer 58 away from the nozzle 50 to resiliently return the frustoconical end 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.
En variante, l'actuateur 40 formé par le transducteur 58 comporte au moins un élément électrostatique ou au moins un élément magnétostrictif.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

REVENDICATIONS
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 (28), dans lequel la culasse (18) porte au moins un dispositif d'injection (30) apte à injecter le carburant vers le bol de combustion (24), caractérisé en ce que le dispositif d'injection (30) comporte au moins un injecteur (32) ultrasonore et en ce que le bol de combustion (24) associé à l'injecteur ultrasonore (36) comporte respectivement une première cavité (34) concave qui, agencée centralement, forme une chambre principale et une deuxième cavité (36) qui, entourant la première cavité, forme une chambre auxiliaire.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 (28), wherein the yoke (18) carries at least an injection device (30) adapted to inject the fuel to the combustion bowl (24), characterized in that the injection device (30) comprises at least one injection ultrasonic injector (32) and in that the combustion bowl (24) associated with the ultrasonic injector (36) respectively comprises a first concave cavity (34) which, arranged centrally, forms a main chamber and a second cavity (36). which, surrounding the first cavity, forms an auxiliary chamber.
2. Moteur selon la revendication 1 , caractérisé en ce que la première cavité (34) du bol de combustion (24) comporte une paroi interne sphérique (38) qui, en coupe axiale, présente un profil globalement curviligne, tel qu'un arc de cercle.2. Motor according to claim 1, characterized in that the first cavity (34) of the combustion bowl (24) comprises a spherical inner wall (38) which, in axial section, has a generally curvilinear profile, such as an arc. circle.
3. Moteur selon l'une des revendications 1 ou 2, caractérisé en ce que la deuxième cavité (36) du bol de combustion (24) comporte une paroi interne (37) qui, en coupe axiale, présente un profil curviligne.3. Motor according to one of claims 1 or 2, characterized in that the second cavity (36) of the combustion bowl (24) has an inner wall (37) which, in axial section, has a curvilinear profile.
4. Moteur selon la revendication 3, caractérisé en ce que la paroi interne (37) de la deuxième cavité (36), s'étendant verticalement à partir du fond (39) du côté de la prem ière cavité (34), présente en coupe axiale un profil tronconique.4. Motor according to claim 3, characterized in that the inner wall (37) of the second cavity (36), extending vertically from the bottom (39) on the side of the first cavity (34), presents in axial section a frustoconical profile.
5. Moteur selon l'une quelconque des revend ications 1 à 4, caractérisé en ce que l'injecteur ultrasonore (32) est apte à injecter le carburant sous la forme d'une nappe d'injection (44) sensiblement conique présentant un faible angle d'ouverture (α) qui, 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), a une valeur comprise entre 20° et 45° de man ière à favoriser la pénétration d u carburant de la nappe (44) dans le bol de combustion (24, 34).5. Motor according to any one of claims 1 to 4, characterized in that the ultrasonic injector (32) is adapted to inject the fuel in the form of a substantially conical injection web (44) having a low opening angle (α) which, determined by the intersection of a mean injection axis (A) of the injection ply and the axis (XX) of the piston (22), has a value between 20 ° and 45 ° to promote fuel penetration of the web (44) into the combustion bowl (24, 34).
6. Moteur selon l'une quelconque des revendications précédentes, caractérisé en ce que le moteur (1 0) est du type à allumage par compression .6. Motor according to any one of the preceding claims, characterized in that the motor (1 0) is of the compression ignition type.
7. Moteur selon l'une quelconque des revendications précédentes, caractérisé en ce que la première cavité (34) du bol de combustion (24) est centrée par rapport au sommet de la nappe d'injection (44) et en ce que l'injecteur ultrasonore (32) est centré sur l'axe (X-X) du piston (22).7. Motor according to any one of the preceding claims, characterized in that the first cavity (34) of the combustion bowl (24) is centered with respect to the top of the injection ply (44) and in that the ultrasonic injector (32) is centered on the axis (XX) of the piston (22).
8. Moteur selon l'une quelconque des revendications précédentes, caractérisé en que l'injecteur ultrasonore (32) comporte un actuateur (40) apte à commander sélectivement des moyens obturateurs (42) pour injecter le carburant et en ce que l'actuateur (40) est formé par un transducteur (58) apte à être commandé pour réal iser sélectivement l'injection de carburant dans le bol de combustion (24, 34) de la chambre de combustion (14).8. Motor according to any one of the preceding claims, characterized in that the ultrasonic injector (32) comprises an actuator (40) adapted to selectively control shutter means (42) for injecting the fuel and in that the actuator ( 40) is formed by a controllable transducer (58) for selectively realizing fuel injection into the combustion bowl (24, 34) of the combustion chamber (14).
9. Moteur selon la revendication 8, caractérisé en que l'actuateur (40, 58) comporte au moins un élément piézoélectrique (70), tel que des céram iques 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.
1 0. Moteur selon la revend ication 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/FR2009/050188 2008-02-06 2009-02-06 Internal combustion engine comprising a double‑cavity combustion bowl for an ultrasonic injector WO2009101341A1 (en)

Applications Claiming Priority (2)

Application Number Priority Date Filing Date Title
FR0850746 2008-02-06
FR0850746A FR2927121B1 (en) 2008-02-06 2008-02-06 INTERNAL COMBUSTION ENGINE HAVING DOUBLE CAVITY COMBUSTION BOWL FOR ULTRASONIC INJECTOR

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WO2009101341A1 true WO2009101341A1 (en) 2009-08-20

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DE102012103212A1 (en) 2012-04-13 2013-10-17 Mwm Gmbh Piston of an internal combustion engine
DE102012103195A1 (en) * 2012-04-13 2013-10-17 Mwm Gmbh Piston of an internal combustion engine
DE102012103206B4 (en) 2012-04-13 2017-08-03 Caterpillar Energy Solutions Gmbh Piston of an internal combustion engine
US20160138518A1 (en) * 2014-11-18 2016-05-19 Caterpillar Inc. Engine Piston
RU195960U1 (en) * 2019-09-09 2020-02-11 Общество с ограниченной ответственностью "Ульяновский автомобильный завод" PISTON OF THE INTERNAL COMBUSTION ENGINE

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JPS58204967A (en) * 1982-05-26 1983-11-29 Hitachi Ltd Cylinder injection engine
JPH09228838A (en) * 1996-02-26 1997-09-02 Shin A C Ii:Kk Direct injection type diesel engine
EP0849448A1 (en) * 1996-12-19 1998-06-24 Cummins Engine Company, Inc. Deep angle injection nozzle and piston having complementary combustion bowl
EP0969191A2 (en) * 1998-07-01 2000-01-05 Man Nutzfahrzeuge Ag Diesel engine piston
EP1172552A1 (en) * 2000-07-13 2002-01-16 Renault Fuel injection device for internal combustion engine

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JPS58204967A (en) * 1982-05-26 1983-11-29 Hitachi Ltd Cylinder injection engine
JPH09228838A (en) * 1996-02-26 1997-09-02 Shin A C Ii:Kk Direct injection type diesel engine
EP0849448A1 (en) * 1996-12-19 1998-06-24 Cummins Engine Company, Inc. Deep angle injection nozzle and piston having complementary combustion bowl
EP0969191A2 (en) * 1998-07-01 2000-01-05 Man Nutzfahrzeuge Ag Diesel engine piston
EP1172552A1 (en) * 2000-07-13 2002-01-16 Renault Fuel injection device for internal combustion engine

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FR2927121B1 (en) 2010-02-12

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