EP0977946A1 - Internal combustion engine fuel injecting device - Google Patents
Internal combustion engine fuel injecting deviceInfo
- Publication number
- EP0977946A1 EP0977946A1 EP98921556A EP98921556A EP0977946A1 EP 0977946 A1 EP0977946 A1 EP 0977946A1 EP 98921556 A EP98921556 A EP 98921556A EP 98921556 A EP98921556 A EP 98921556A EP 0977946 A1 EP0977946 A1 EP 0977946A1
- Authority
- EP
- European Patent Office
- Prior art keywords
- fuel
- injection device
- injector
- fuel injection
- nozzle
- Prior art date
- Legal status (The legal status is an assumption and is not a legal conclusion. Google has not performed a legal analysis and makes no representation as to the accuracy of the status listed.)
- Withdrawn
Links
- 239000000446 fuel Substances 0.000 title claims abstract description 88
- 238000002485 combustion reaction Methods 0.000 title claims abstract description 19
- 238000002347 injection Methods 0.000 claims abstract description 55
- 239000007924 injection Substances 0.000 claims abstract description 55
- 230000010355 oscillation Effects 0.000 claims abstract description 9
- 125000004122 cyclic group Chemical group 0.000 claims abstract description 8
- 230000009471 action Effects 0.000 claims description 6
- 239000002828 fuel tank Substances 0.000 claims description 4
- 230000010358 mechanical oscillation Effects 0.000 claims description 2
- 230000001105 regulatory effect Effects 0.000 claims 1
- 238000005452 bending Methods 0.000 description 9
- 239000007788 liquid Substances 0.000 description 9
- 239000000463 material Substances 0.000 description 6
- 230000000694 effects Effects 0.000 description 5
- 230000033001 locomotion Effects 0.000 description 4
- 238000011144 upstream manufacturing Methods 0.000 description 4
- 239000012528 membrane Substances 0.000 description 3
- 238000009834 vaporization Methods 0.000 description 3
- 230000008016 vaporization Effects 0.000 description 3
- 230000015572 biosynthetic process Effects 0.000 description 2
- 230000008859 change Effects 0.000 description 2
- 238000006073 displacement reaction Methods 0.000 description 2
- 210000000887 face Anatomy 0.000 description 2
- 239000012530 fluid Substances 0.000 description 2
- 230000005499 meniscus Effects 0.000 description 2
- 239000000203 mixture Substances 0.000 description 2
- 210000001331 nose Anatomy 0.000 description 2
- 238000002360 preparation method Methods 0.000 description 2
- 230000004044 response Effects 0.000 description 2
- 238000009736 wetting Methods 0.000 description 2
- 238000005299 abrasion Methods 0.000 description 1
- 230000001154 acute effect Effects 0.000 description 1
- 238000004026 adhesive bonding Methods 0.000 description 1
- 230000003321 amplification Effects 0.000 description 1
- 230000033228 biological regulation Effects 0.000 description 1
- 230000006735 deficit Effects 0.000 description 1
- 239000006185 dispersion Substances 0.000 description 1
- 238000009826 distribution Methods 0.000 description 1
- 239000003344 environmental pollutant Substances 0.000 description 1
- 238000001704 evaporation Methods 0.000 description 1
- 230000008020 evaporation Effects 0.000 description 1
- 230000005284 excitation Effects 0.000 description 1
- 239000007789 gas Substances 0.000 description 1
- 210000003128 head Anatomy 0.000 description 1
- 230000006872 improvement Effects 0.000 description 1
- 230000014759 maintenance of location Effects 0.000 description 1
- 238000004519 manufacturing process Methods 0.000 description 1
- 238000003199 nucleic acid amplification method Methods 0.000 description 1
- 230000003534 oscillatory effect Effects 0.000 description 1
- 231100000719 pollutant Toxicity 0.000 description 1
- 230000000750 progressive effect Effects 0.000 description 1
- 230000001737 promoting effect Effects 0.000 description 1
- 238000005507 spraying Methods 0.000 description 1
Classifications
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- 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
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- 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
- F02M61/16—Details not provided for in, or of interest apart from, the apparatus of groups F02M61/02 - F02M61/14
- F02M61/18—Injection nozzles, e.g. having valve seats; Details of valve member seated ends, not otherwise provided for
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- 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
- 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
- F02M69/042—Positioning of injectors with respect to engine, e.g. in the air intake conduit
- F02M69/044—Positioning of injectors with respect to engine, e.g. in the air intake conduit for injecting into the intake conduit downstream of an air throttle valve
Definitions
- the present invention relates to a fuel injection device for an internal combustion engine intended in particular to equip a motor vehicle.
- the invention relates more particularly to a fuel injection device using a piezoelectric actuator to atomize the fuel injected in the form of very fine droplets.
- the fuel injection devices used today on internal combustion engines fitted to motor or road vehicles conventionally operate on the model of a valve, the open or closed state of which is continuously controlled, the dosage of the injected fuel then done directly by the opening time.
- Such injection systems include an electric fuel supply pump which supplies, via a distribution manifold, all of the injectors under a pressure having a constant difference with the pressure prevailing in the intake manifold. through a pressure regulator.
- an electric fuel supply pump which supplies, via a distribution manifold, all of the injectors under a pressure having a constant difference with the pressure prevailing in the intake manifold. through a pressure regulator.
- the electromagnet actuating the valve of each injector By electronically controlling the electromagnet actuating the valve of each injector, the start and the opening time of the latter are controlled and a precise flow of fuel is determined for each of the injectors, thus the quantity of fuel injected depends only the opening time of the electro-injectors.
- the injectors of the electromagnetically controlled needle type which are the most commonly used, however have limits which hinder the improvement of engine performance, in particular in terms of pollution control.
- the times taken to open or close the needles are still too high, around 1 to 2 ms, which prevents the injection from being distributed correctly over the entire opening time of the valve.
- the minimum opening time which determines the minimum dose of fuel that can be injected, is still too long for certain engine operating points.
- Known needle injectors also have injection holes of relatively large diameters to allow the delivery of the required quantities of fuel for operations at full load and high engine speeds. This arrangement generates fuel jets having drops of large dimensions, which slows down the vaporization of the fuel (and therefore the preparation of the fuel mixture) and is capable of promoting the phenomenon of wall wetting.
- the non-vaporized fuel tends to settle on the walls of the intake duct or the combustion chamber (by direct injection).
- Such a deposit causes metering problems, particularly acute in the transients due to a lack of knowledge of the amount of fuel which actually enters the corresponding combustion chamber.
- This phenomenon of wall wetting is one of the major causes of high pollutant emissions during cold engine starts.
- the object of the present invention is therefore to solve all of these problems by proposing an injection device capable of delivering a cloud of fuel drops whose sizes are perfectly calibrated to ensure precise metering and sufficiently small to ensure the complete and homogeneous spraying of the injected fuel.
- the fuel injection device for an internal combustion engine is of the type comprising an injector connected to a fuel supply circuit under a suitable pressure, this injector comprising an injection nozzle at the end of which at least one fuel injection orifice is provided.
- the injection device is characterized in that the injector cooperates with means of cyclic vibration controlled by the electronic engine control system so as to cause mechanical oscillations in bending of the injection nozzle , this injection nozzle being adapted to eject a predetermined quantity of fuel at each of its oscillations.
- the injection nozzle is formed by a plurality of channels of suitable dimensions, joined together in a bundle.
- the channels forming the injection nozzle are adapted to be supplied with fuel by capillarity.
- these channels have injection orifices adapted to eject the fuel in the form of droplets of given sizes.
- the injector has an elastically deformable part which cooperates with the means for cyclic vibration controlled by the electronic engine control system, the injection nozzle being secured to this deformable part.
- this elastically deformable part is formed by a chamber extending in the extension of a fuel tank to which the fuel supply circuit is connected by the 'through a pilot valve whose opening is controlled according to the filling level of said tank.
- the fuel tank incorporated in the injector cooperates with regulation means making it possible to adjust the pressure to the pressure prevailing in the engine air intake circuit.
- the vibration setting means are formed by a piezoelectric actuator.
- Such an electronically controlled injection device allows very precise control of the size of the drops injected and, moreover, is completely independent of the flow rate and the duration of injection.
- FIG. 1 represents an overall view of the injection device according to the invention
- Figures 2A and 2B are views in longitudinal section of the injection device of Figure 1 detailing its operation;
- Figure 3 is a partial sectional view of an intake duct of an internal combustion engine equipped with a fuel injection device according to the invention.
- FIG. 3 there is seen in cross section an intake duct 12 formed through the cylinder head 16 of an internal combustion engine of the multicylinder type with spark ignition.
- This duct 12 opens out through an inlet orifice on the underside of the cylinder head 16 defining the roof of a combustion chamber 15.
- This inlet orifice conventionally serves as a seat for a stem valve 13 slidably mounted in a housed guide in the cylinder head 16.
- the opening of the valve 13 is controlled by suitable means, not shown, such as a camshaft.
- the fuel supply to the engine is of the electronically controlled multipoint type by which each combustion chamber 15 is supplied with fuel by at least one fuel injector 1.
- the injector 1 extends, according to the particular embodiment shown, directly into one of the intake ducts serving the combustion chamber 15, in this case the duct 12.
- the injector 1 is arranged so that its ejection nozzle 8 is directed towards the head of the valve 13 in order to direct the jet of fuel 11 directly into the combustion chamber 15 through the intake orifice, when the opening of the valve 13.
- the body of the injector 1 is fixed in the cylinder head 16 by its end upper, which is also connected to a fuel supply line 2.
- the injector body comprises, in its upstream part in the direction of flow of the fuel, a buffer tank 4 having a membrane 5 for pressurizing.
- This tank 4 is supplied by a line 2 for supplying the fuel under a suitable pressure.
- an electrically controlled valve 3 whose function is to control the filling level of the tank 4.
- the reservoir 4 communicates with a chamber 7, the elastically deformable walls of which cooperate with cyclic pressurization means such as a plate made of piezoelectric material 6.
- the chamber 7 is extended by a nozzle 8 formed by a plurality of inlet channels 9 of the fuel of progressive sections, arranged in a bundle. This nozzle 8 is integral with the chamber 7 so that the cyclic deformations of the latter under the action of the pressurizing means, causes the vibration of the nozzle 8 and the ejection of the fuel.
- the channels 9 open at the downstream end 14 of the nozzle 8 through suitable orifices forming injection noses 10 through which the fuel is ejected in the form of a jet 11 of droplets of suitable sizes.
- These channels have shapes and are made of materials adapted to allow the creation of sufficient capillary forces necessary for filling them with fuel from chamber 7.
- the tank is kept filled by controlling the valve 3.
- the valve 3 When the quantity of fuel in the tank 4 falls below a given threshold, detected by a sensor not shown here, the valve 3 is then opened until the filling of the tank 4 at the required threshold, then valve 3 is closed again.
- the variations in volume in the tank 4 due to the quantities of fuel ejected through the orifices 10 and to the quantities of fuel passing through the valve 3 are sufficiently small compared to the total volume of the tank 4 so that the variations in pressure can be compensated by the pressurizing membrane 5.
- the pressure of the supply circuit can be relatively low and the valve of simplified design, in particular have a response time much longer than that of a conventional injector.
- the shape of the chamber 7, between points A and D, and the nature of the materials used for the production of its walls, are therefore adapted so as to generate, under the action of the cyclic pressurization means 6, an oscillation of the nozzle 8 whose amplitude is maximum at the orifices 10 of the channels 9.
- the piezoelectric plate 6 is secured to the wall of the chamber 7 by gluing and its electrodes are formed by two parallel faces, l 'one (AD) being in contact with one injector at the wall of the chamber 7 and the other (CB) having its free surface.
- the piezoelectric plate 6 is polarized in a direction perpendicular to the electrodes, so that when a voltage is applied between these electrodes, by necking effect the piezoelectric plate 6 stretches in its two planar directions, the state of stress on the two faces being different this has the effect of creating a bending of the plate which results locally in a change of curvature of the wall of the chamber 7.
- the bending of the wall of the chamber 7 causes in bending the part 8 of the body 1, namely the injection nozzle, with maximum displacement at its end 14 at the orifices 10.
- the displacement generated at the end of the nozzle 14 makes it possible to expel through each orifice 10 a micro-quantity of liquid which gives rise to a drop 11 ejected with a certain speed.
- each cycle of electric voltage applied to the piezoelectric plate 6 it passes through two symmetrical bending deformation states which causes the end of the nozzle 14 to oscillate between two symmetrical positions E and F linked to an amplitude given oscillation.
- the fuel drops are ejected.
- two drops of fuel are ejected per orifice.
- the ejection of the drops through the orifices 10 at the end 14 of the nozzle 8 is effected by the sole action of the oscillatory movement in bending of the latter.
- Oscillating movement in bending which causes on the one hand a local overpressure in the liquid at the level of the nozzle and on the other hand a setting in motion of the same liquid confined in the nozzle, the two effects contributing simultaneously to the formation and to the ejection of the drops.
- the shape of the injector 1 and more particularly of the nozzle 8, is therefore suitable for obtaining a natural amplification of the movement.
- the beam structure of the channels 9 perfectly meets this objective. Likewise, it is important that the structure chosen can reach high resonant frequencies allowing the injection of a high number of drops of fuel per second.
- the injector according to the invention therefore operates without a valve since the channels 9 open freely to the atmosphere, the retention of the liquid in the nozzle 8 operating simply by virtue of the surface tension of the liquid and the action of the capillary forces.
- a liquid meniscus is thus naturally formed on each orifice 10 of the nozzle 8, a meniscus which prevents the flow of fluid as long as the pressure difference between the liquid contained in the nozzle and the surrounding atmosphere does not exceed a given value.
- the injection device comprises a body 1 which in its part supporting the piezoelectric plate 6 measures 1 millimeter in total and about 1 centimeter in its width and its length, the nozzle has a length close to 20 millimeters and a thickness of the order of 0.2 millimeters at its end where is located a row of circular orifices 10 30 microns in diameter.
- a double beam of drops with excitation frequencies ranging from 40 kH to 400 kH, and this for an applied alternating voltage of the order of 10 volts peak.
- the diameter of the drops is a function of the amplitude of the applied voltage and the operating frequency.
- the speed of the drops depending on the operating point chosen varies from 5 to 15 meters per second.
- the response time of the device for an oscillation of the nozzle and the simultaneous ejection of drops of fuel is approximately 10 microseconds.
- a device operating at 250 kH has 170 orifices 10 of 30 microns in diameter at the end of the nozzle.
- the injector 1 independently of the advantages which it presents in terms of metering and vaporization of the fuel, thanks in particular to the precise calibration which it allows for the size of the droplets, is moreover particularly suitable for operating the fuel injection when the intake valve 13 is lifted and thus inject the fuel directly into the combustion chamber 15.
- This flow assists the ejection of fuel and drives the drops which are ejected in a bundle of the orifices 10 to propel them directly into the chamber 15 through the opening of the valve.
- the difference between the ejection speed of the drops, between 5 and 10 meters per second and that of the air flow, causes abrasion of the fuel drops and contributes to their evaporation.
- the body 1 of the injector can thus be placed closer to the neck of the valve 13 or more upstream in the intake duct 12, see outside of the intake duct in an arrangement provided in the cylinder head , the end of the nozzle 8 opening into the intake duct 12 at a point located either near the neck of the valve or further upstream.
- the injection orifices can be circular, square or any other geometric shape, the transverse dimensions of the orifices being able to be reduced to a few microns, for example of the order of ten to thirty microns .
- the section of the orifices makes it possible to calibrate the size of the drops formed, the calibration of the size of the drops can then be modified by varying the amplitude of oscillation of the nozzle.
Landscapes
- Engineering & Computer Science (AREA)
- Chemical & Material Sciences (AREA)
- Combustion & Propulsion (AREA)
- Mechanical Engineering (AREA)
- General Engineering & Computer Science (AREA)
- Fuel-Injection Apparatus (AREA)
Abstract
The invention concerns an internal combustion engine fuel injecting device (1) connected to a circuit (2) supplying fuel under adapted pressure, said injector (1) comprising an injection nozzle (8) at the end (14) of which is arranged at least an aperture for injecting fuel (10). The invention is characterised in that said injector (1) co-operates with cyclic vibration means (6) controlled by the engine electronic control system to cause the injection nozzle (8) to vibrate, said injection nozzle (8) being adapted to eject a predetermined amount of fuel at each one of its oscillations.
Description
DISPOSITIF D'INJECTION DE CARBURANT POUR MOTEUR A COMBUSTION INTERNE FUEL INJECTION DEVICE FOR INTERNAL COMBUSTION ENGINE
La présente invention se rapporte à un dispositif d'injection de carburant pour moteur à combustion interne destiné notamment à équiper un véhicule automobile. L'invention concerne plus particulièrement un dispositif d'injection de carburant utilisant un actuateur piézo-électrique pour atomiser le carburant injecté sous forme de très fines gouttelettes.The present invention relates to a fuel injection device for an internal combustion engine intended in particular to equip a motor vehicle. The invention relates more particularly to a fuel injection device using a piezoelectric actuator to atomize the fuel injected in the form of very fine droplets.
Les dispositifs d'injection de carburant utilisés aujourd'hui sur les moteurs à combustion interne équipant les véhicules automobiles ou routiers, fonctionnent classiquement sur le modèle d'une vanne dont on commande en permanence l'état ouvert ou fermé, le dosage du carburant injecté se faisant alors directement par le temps d'ouverture.The fuel injection devices used today on internal combustion engines fitted to motor or road vehicles, conventionally operate on the model of a valve, the open or closed state of which is continuously controlled, the dosage of the injected fuel then done directly by the opening time.
De tels systèmes d'injection comprennent une pompe électrique d'alimentation en carburant qui alimente, par le canal d'une rampe de distribution, l'ensemble des injecteurs sous une pression présentant une différence constante avec la pression régnant dans le collecteur d'admission grâce à un régulateur de pression. En contrôlant électroniquement 1 'électro-aimant actionnant la soupape de chaque injecteur, on commande le début et la durée d'ouverture de celle-ci et on détermine alors un débit précis de carburant pour chacun des injecteurs, ainsi la quantité de carburant injectée dépend uniquement du temps d'ouverture des électro- injecteurs.
Les injecteurs du type à aiguille commandée électromagnétiquement, qui sont les plus communément employés, présentent toutefois des limites qui freinent l'amélioration des performances des moteurs notamment en terme de dépollution. En particulier les temps mis pour ouvrir ou fermer les aiguilles sont encore trop élevés, d'environ 1 à 2 ms, ce qui empêche de répartir correctement l'injection sur tout le temps d'ouverture de la soupape. De plus, le temps minimum d'ouverture, qui détermine la dose minimale de carburant pouvant être injecté, est encore trop important pour certains points de fonctionnement moteur .Such injection systems include an electric fuel supply pump which supplies, via a distribution manifold, all of the injectors under a pressure having a constant difference with the pressure prevailing in the intake manifold. through a pressure regulator. By electronically controlling the electromagnet actuating the valve of each injector, the start and the opening time of the latter are controlled and a precise flow of fuel is determined for each of the injectors, thus the quantity of fuel injected depends only the opening time of the electro-injectors. The injectors of the electromagnetically controlled needle type, which are the most commonly used, however have limits which hinder the improvement of engine performance, in particular in terms of pollution control. In particular, the times taken to open or close the needles are still too high, around 1 to 2 ms, which prevents the injection from being distributed correctly over the entire opening time of the valve. In addition, the minimum opening time, which determines the minimum dose of fuel that can be injected, is still too long for certain engine operating points.
Les injecteurs à aiguille connus présentent par ailleurs des orifices d'injection de diamètres relativement importants pour permettre de débiter les quantités requises de carburant pour les fonctionnements à pleine charge et hauts régimes des moteurs. Cette disposition génère des jets de carburant présentant des gouttes de fortes dimensions, ce qui freine la vaporisation du carburant (et donc la préparation du mélange carburé) et est à même de favoriser le phénomène de mouillage de paroi.Known needle injectors also have injection holes of relatively large diameters to allow the delivery of the required quantities of fuel for operations at full load and high engine speeds. This arrangement generates fuel jets having drops of large dimensions, which slows down the vaporization of the fuel (and therefore the preparation of the fuel mixture) and is capable of promoting the phenomenon of wall wetting.
En effet, le carburant non vaporisé tend à se déposer sur les parois du conduit d'admission ou de la chambre de combustion (en injection directe) . Un tel dépôt entraîne des problèmes de dosage, particulièrement aigus dans les transitoires par manque de connaissance de la quantité de carburant qui rentre effectivement dans la chambre de combustion correspondante. Ce phénomène de
mouillage des parois est l'une des causes importantes des fortes émissions de polluants lors des démarrages à froid des moteurs.In fact, the non-vaporized fuel tends to settle on the walls of the intake duct or the combustion chamber (by direct injection). Such a deposit causes metering problems, particularly acute in the transients due to a lack of knowledge of the amount of fuel which actually enters the corresponding combustion chamber. This phenomenon of wall wetting is one of the major causes of high pollutant emissions during cold engine starts.
Par ailleurs, avec un injecteur classique à aiguille, à l'ouverture de l'aiguille lorsque cette dernière commence à quitter son siège, il se forme un bulbe de liquide qui disparaît lorsque l'aiguille est complètement levée, l'écoulement du fluide se régularisant alors. Ce changement dans la nature de l'écoulement rend impossible tout contrôle précis du débit instantané de l' injecteur.In addition, with a conventional needle injector, when the needle opens when the latter begins to leave its seat, a liquid bulb forms which disappears when the needle is fully raised, the fluid flow regularizing then. This change in the nature of the flow makes any precise control of the instantaneous injector flow impossible.
Certains ont cherché à résoudre ces différents problèmes, en développant des injecteurs utilisant des actuateurs piézo-électriques pour manoeuvrer l'aiguille de façon à abaisser la durée d'ouverture et de fermeture de l'aiguille, mais de tels systèmes qui fonctionnent toujours selon le principe d'une vanne, conservent des inconvénients importants liés notamment à la dispersion importante affectant la taille des gouttes dans le jet de carburant au sortir du nez de l' injecteur.Some have sought to solve these various problems, by developing injectors using piezoelectric actuators to maneuver the needle so as to reduce the duration of opening and closing of the needle, but such systems which always operate according to the principle of a valve, retain significant drawbacks related in particular to the significant dispersion affecting the size of the drops in the fuel jet leaving the nose of the injector.
L'ensemble des problèmes cités précédemment se solde donc par une vaporisation du carburant pouvant être incomplète et non homogène lors de la préparation du mélange carburé dans la chambre de combustion, des dosages imprécis, avec pour conséquence une combustion incomplète se traduisant par la formation d'une quantité élevée de gaz polluants et un déficit énergétique altérant le rendement du moteur.
L'objet de la présente invention est donc de résoudre l'ensemble de ces problèmes en proposant un dispositif d'injection apte à délivrer un nuage de gouttes de carburant dont les tailles sont parfaitement calibrées pour assurer un dosage précis et suffisamment petites pour assurer la vaporisation complète et homogène du carburant injecté.All the problems mentioned above therefore result in a vaporization of the fuel which may be incomplete and non-homogeneous during the preparation of the fuel mixture in the combustion chamber, imprecise dosages, with the result of incomplete combustion resulting in the formation of '' a high quantity of polluting gases and an energy deficit affecting engine performance. The object of the present invention is therefore to solve all of these problems by proposing an injection device capable of delivering a cloud of fuel drops whose sizes are perfectly calibrated to ensure precise metering and sufficiently small to ensure the complete and homogeneous spraying of the injected fuel.
Le dispositif d'injection de carburant pour moteur à combustion interne selon 1 ' invention est du type comprenant un injecteur relié à un circuit d'alimentation en carburant sous une pression adaptée, cet injecteur comportant une buse d'injection à l'extrémité de laquelle est ménagé au moins un orifice d'injection de carburant.The fuel injection device for an internal combustion engine according to the invention is of the type comprising an injector connected to a fuel supply circuit under a suitable pressure, this injector comprising an injection nozzle at the end of which at least one fuel injection orifice is provided.
Selon l'invention, le dispositif d'injection est caractérisé en ce que l' injecteur coopère avec des moyens de mise en vibration cyclique pilotés par le système électronique de contrôle moteur de façon à provoquer des oscillations mécaniques en flexion de la buse d'injection, cette buse d'injection étant adaptée pour éjecter une quantité de carburant prédéterminée à chacune de ses oscillations.According to the invention, the injection device is characterized in that the injector cooperates with means of cyclic vibration controlled by the electronic engine control system so as to cause mechanical oscillations in bending of the injection nozzle , this injection nozzle being adapted to eject a predetermined quantity of fuel at each of its oscillations.
Selon une autre caractéristique du dispositif d'injection de carburant objet de l'invention, la buse d'injection est formée par une pluralité de canaux de dimensions adaptées, réunis en faisceau.According to another characteristic of the fuel injection device which is the subject of the invention, the injection nozzle is formed by a plurality of channels of suitable dimensions, joined together in a bundle.
Selon une autre caractéristique du dispositif d'injection de carburant objet de
l'invention, les canaux formant la buse d'injection sont adaptés pour être alimentés en carburant par capillarité.According to another characteristic of the fuel injection device object of the invention, the channels forming the injection nozzle are adapted to be supplied with fuel by capillarity.
Selon une autre caractéristique du dispositif d'injection de carburant objet de l'invention, ces canaux présentent des orifices d'injection adaptée pour éjecter le carburant sous forme de gouttelettes de tailles données.According to another characteristic of the fuel injection device which is the subject of the invention, these channels have injection orifices adapted to eject the fuel in the form of droplets of given sizes.
Selon une autre caractéristique du dispositif d'injection de carburant objet de l'invention, l' injecteur présente une partie élastiquement déformable qui coopère avec les moyens de mise en vibration cyclique pilotés par le système électronique de contrôle moteur, la buse d'injection étant solidaire de cette partie déformable.According to another characteristic of the fuel injection device which is the subject of the invention, the injector has an elastically deformable part which cooperates with the means for cyclic vibration controlled by the electronic engine control system, the injection nozzle being secured to this deformable part.
Selon une autre caractéristique du dispositif d'injection de carburant objet de l'invention, cette partie élastiquement déformable est formée par une chambre s 'étendant dans le prolongement d'un réservoir de carburant auquel est connecté le circuit d'alimentation en carburant par l'intermédiaire d'une vanne pilotée dont l'ouverture est commandée en fonction du niveau de remplissage dudit réservoir.According to another characteristic of the fuel injection device which is the subject of the invention, this elastically deformable part is formed by a chamber extending in the extension of a fuel tank to which the fuel supply circuit is connected by the 'through a pilot valve whose opening is controlled according to the filling level of said tank.
Selon une autre caractéristique du dispositif d'injection de carburant objet de l'invention, le réservoir de carburant incorporé à 1' injecteur coopère avec des moyens de régulation permettant d'ajuster la pression à la pression
régnant dans le circuit d'admission d'air du moteur.According to another characteristic of the fuel injection device which is the subject of the invention, the fuel tank incorporated in the injector cooperates with regulation means making it possible to adjust the pressure to the pressure prevailing in the engine air intake circuit.
Selon une autre caractéristique du dispositif d'injection de carburant objet de l'invention, les moyens de mise en vibration sont formés par un actuateur piézo-électrique.According to another characteristic of the fuel injection device which is the subject of the invention, the vibration setting means are formed by a piezoelectric actuator.
Un tel dispositif d'injection commandé électroniquement permet un contrôle très précis de la taille des gouttes injectées et qui plus est totalement indépendant du débit et de la durée d' injection.Such an electronically controlled injection device allows very precise control of the size of the drops injected and, moreover, is completely independent of the flow rate and the duration of injection.
Les caractéristiques et avantages de la présente invention sont présentées de manière plus détaillée ci-après en décrivant un mode de réalisation de l'invention, à titre d'exemple non limitatif, la description faisant référence aux dessins annexés dans lesquels:The characteristics and advantages of the present invention are presented in more detail below by describing an embodiment of the invention, by way of nonlimiting example, the description referring to the appended drawings in which:
la figure 1 représente une vue d'ensemble du dispositif d'injection selon l'invention ;FIG. 1 represents an overall view of the injection device according to the invention;
les figures 2A et 2B sont des vues en coupe longitudinale du dispositif d'injection de la figure 1 précisant son fonctionnement ;Figures 2A and 2B are views in longitudinal section of the injection device of Figure 1 detailing its operation;
la figure 3 est une vue en coupe partielle d'un conduit d'admission d'un moteur à combustion interne équipé d'un dispositif d'injection de carburant selon l'invention.Figure 3 is a partial sectional view of an intake duct of an internal combustion engine equipped with a fuel injection device according to the invention.
Conformément aux dessins annexés, seuls les éléments nécessaires à la compréhension de
l'invention ont été représentés. De plus, pour faciliter la lecture de ces dessins, les mêmes pièces portent les mêmes références d'une figure à l'autre.In accordance with the accompanying drawings, only the elements necessary for the understanding of the invention have been shown. In addition, to facilitate reading of these drawings, the same parts have the same references from one figure to another.
En se reportant à la figure 3, on voit en coupe transversale un conduit d'admission 12 ménagé à travers la culasse 16 d'un moteur à combustion interne du type multicylindre à allumage commandé. Ce conduit 12 débouche par un orifice d'admission sur la face inférieure de la culasse 16 définissant le toit d'une chambre de combustion 15. Cet orifice d'admission sert classiquement de siège à une soupape à tige 13 montée coulissante dans un guide logé dans la culasse 16. L'ouverture de la soupape 13 est commandée des moyens appropriés non figurés, tels qu'un arbre à cames.Referring to Figure 3, there is seen in cross section an intake duct 12 formed through the cylinder head 16 of an internal combustion engine of the multicylinder type with spark ignition. This duct 12 opens out through an inlet orifice on the underside of the cylinder head 16 defining the roof of a combustion chamber 15. This inlet orifice conventionally serves as a seat for a stem valve 13 slidably mounted in a housed guide in the cylinder head 16. The opening of the valve 13 is controlled by suitable means, not shown, such as a camshaft.
L'alimentation en carburant du moteur est du type multipoint à commande électronique par lequel chaque chambre de combustion 15 est alimentée en carburant par au moins un injecteur de carburant 1. L' injecteur 1 s'étend, selon le mode particulier de réalisation représenté, directement dans l'un des conduits d'admission desservant la chambre de combustion 15, en l'occurrence le conduit 12.The fuel supply to the engine is of the electronically controlled multipoint type by which each combustion chamber 15 is supplied with fuel by at least one fuel injector 1. The injector 1 extends, according to the particular embodiment shown, directly into one of the intake ducts serving the combustion chamber 15, in this case the duct 12.
L' injecteur 1 est disposé de façon que sa buse d'éjection 8 soit dirigée vers la tête de la soupape 13 afin de diriger le jet de carburant 11 directement dans la chambre de combustion 15 à travers l'orifice d'admission, lors de l'ouverture de la soupape 13. Le corps de l' injecteur 1 est fixé dans la culasse 16 par son extrémité
supérieure, laquelle est par ailleurs connectée à une conduite 2 d'amenée du carburant.The injector 1 is arranged so that its ejection nozzle 8 is directed towards the head of the valve 13 in order to direct the jet of fuel 11 directly into the combustion chamber 15 through the intake orifice, when the opening of the valve 13. The body of the injector 1 is fixed in the cylinder head 16 by its end upper, which is also connected to a fuel supply line 2.
En se reportant à la figure 1, on a détaillé le corps de l' injecteur 1 objet de la présente invention. Le corps de l' injecteur comprend, dans sa partie amont dans le sens d'écoulement du carburant, un réservoir tampon 4 possédant une membrane 5 de mise à pression. Ce réservoir 4 est alimenté par une conduite 2 d'amenée du carburant sous une pression adaptée. Entre la conduite 2 et le réservoir 4 est interposée une vanne 3 commandée électriquement dont la fonction est de contrôler le niveau de remplissage du réservoir 4.Referring to FIG. 1, the body of the injector 1 which is the subject of the present invention has been detailed. The injector body comprises, in its upstream part in the direction of flow of the fuel, a buffer tank 4 having a membrane 5 for pressurizing. This tank 4 is supplied by a line 2 for supplying the fuel under a suitable pressure. Between the pipe 2 and the tank 4 is interposed an electrically controlled valve 3 whose function is to control the filling level of the tank 4.
Le réservoir 4 communique avec une chambre 7 dont les parois élastiquement déformables coopèrent avec des moyens de mise en pression cyclique telle qu'une plaquette en matériau piézoélectrique 6. La chambre 7 est prolongée par une buse 8 formée par une pluralité de canaux d'amenée 9 du carburant de sections évolutives, disposés en faisceau. Cette buse 8 est solidaire de la chambre 7 de façon que les déformations cycliques de cette dernière sous l'action des moyens de mise en pression, entraîne la vibration de la buse 8 et l'éjection du carburant.The reservoir 4 communicates with a chamber 7, the elastically deformable walls of which cooperate with cyclic pressurization means such as a plate made of piezoelectric material 6. The chamber 7 is extended by a nozzle 8 formed by a plurality of inlet channels 9 of the fuel of progressive sections, arranged in a bundle. This nozzle 8 is integral with the chamber 7 so that the cyclic deformations of the latter under the action of the pressurizing means, causes the vibration of the nozzle 8 and the ejection of the fuel.
Les canaux 9 débouchent à 1 ' extrémité avale 14 de la buse 8 par des orifices adaptés formant des nez d'injection 10 à travers lesquels est éjecté le carburant sous la forme d'un jet 11 de gouttelettes de tailles adaptées. Ces canaux ont des formes et sont réalisés dans des matériaux
adaptés pour permettre la création de forces capillaires suffisantes nécessaires à leur remplissage en carburant depuis la chambre 7.The channels 9 open at the downstream end 14 of the nozzle 8 through suitable orifices forming injection noses 10 through which the fuel is ejected in the form of a jet 11 of droplets of suitable sizes. These channels have shapes and are made of materials adapted to allow the creation of sufficient capillary forces necessary for filling them with fuel from chamber 7.
Conformément aux figures 2a et 2b, le fonctionnement de l' injecteur 1 qui vient d'être décrit est le suivant. La vanne 3 étant normalement maintenue fermée, la pression du carburant remplissant le réservoir 4 suit la pression régnant dans le conduit d'admission 12 grâce à la membrane de mise à pression 5. L'équilibre de pression régnant entre l'intérieur du corps de l' injecteur 1 et l'extérieur de ce dernier conjugué à la forme adaptée des conduits 9, permettent d'assurer par capillarité le remplissage des conduits 9 en carburant depuis la chambre 7 et le réservoir 4 au fur et à mesure de l'éjection du carburant, tout en retenant le carburant à 1 ' intérieur des canaux 9 en l'absence de vibration de ces derniers par la tension de surface agissant au droit des orifices 10.According to Figures 2a and 2b, the operation of the injector 1 which has just been described is as follows. The valve 3 being normally kept closed, the pressure of the fuel filling the tank 4 follows the pressure prevailing in the intake duct 12 by virtue of the pressurizing membrane 5. The pressure balance prevailing between the interior of the body of the injector 1 and the outside of the latter combined with the suitable shape of the conduits 9, make it possible to ensure by capillary filling of the conduits 9 with fuel from the chamber 7 and the reservoir 4 as and when ejection of the fuel, while retaining the fuel inside the channels 9 in the absence of vibration of the latter by the surface tension acting at the level of the orifices 10.
Le réservoir est maintenu rempli grâce au pilotage de la vanne 3. Lorsque la quantité de carburant dans le réservoir 4 passe en dessous d'un seuil donné, détecté par un capteur non figuré ici, la vanne 3 est alors ouverte jusqu'au remplissage du réservoir 4 au seuil requis, puis la vanne 3 est à nouveau fermée. Les variations de volume dans le réservoir 4 dues aux quantités de carburant éjectées à travers les orifices 10 et aux quantités de carburant traversant la vanne 3 sont suffisamment faibles comparées au volume total du réservoir 4 pour que les variations de pression
puissent être compensées par la membrane 5 de mise à pression.The tank is kept filled by controlling the valve 3. When the quantity of fuel in the tank 4 falls below a given threshold, detected by a sensor not shown here, the valve 3 is then opened until the filling of the tank 4 at the required threshold, then valve 3 is closed again. The variations in volume in the tank 4 due to the quantities of fuel ejected through the orifices 10 and to the quantities of fuel passing through the valve 3 are sufficiently small compared to the total volume of the tank 4 so that the variations in pressure can be compensated by the pressurizing membrane 5.
Ainsi, conformément à l'invention, la pression du circuit d'alimentation peut être relativement faible et la valve de conception simplifiée, notamment avoir un temps de réponse beaucoup plus long que celui d'un injecteur classique.Thus, in accordance with the invention, the pressure of the supply circuit can be relatively low and the valve of simplified design, in particular have a response time much longer than that of a conventional injector.
La forme de la chambre 7, comprise entre les points A et D, et la nature des matériaux utilisés par la réalisation de ses parois, sont donc adaptées de façon à générer sous l'action des moyens de mise en pression cyclique 6 une oscillation de la buse 8 dont l'amplitude est maximale au niveau des orifices 10 des canaux 9. Pour ce faire, la plaquette piézo-électrique 6 est solidarisée à la paroi de la chambre 7 par collage et ses électrodes sont formées par deux faces parallèles, l'une (A D) étant en contact avec 1' injecteur au niveau de la paroi de la chambre 7 et l'autre (C B) ayant sa surface libre.The shape of the chamber 7, between points A and D, and the nature of the materials used for the production of its walls, are therefore adapted so as to generate, under the action of the cyclic pressurization means 6, an oscillation of the nozzle 8 whose amplitude is maximum at the orifices 10 of the channels 9. To do this, the piezoelectric plate 6 is secured to the wall of the chamber 7 by gluing and its electrodes are formed by two parallel faces, l 'one (AD) being in contact with one injector at the wall of the chamber 7 and the other (CB) having its free surface.
La plaquette piézo-électrique 6 est polarisée dans une direction perpendiculaire aux électrodes, de sorte que lorsque l'on applique une tension entre ces électrodes, par effet de striction la plaquette piézo-électrique 6 s'étire dans ses deux directions planaires, l'état de contrainte sur les deux faces étant différents ceci a pour effet de créer une flexion de la plaquette qui se traduit localement par un changement de courbure de la paroi de la chambre 7. La flexion de la paroi de la chambre 7 entraîne en flexion la
partie 8 du corps 1, à savoir la buse d'injection, avec un maximum de déplacement à son extrémité 14 au niveau des orifices 10.The piezoelectric plate 6 is polarized in a direction perpendicular to the electrodes, so that when a voltage is applied between these electrodes, by necking effect the piezoelectric plate 6 stretches in its two planar directions, the state of stress on the two faces being different this has the effect of creating a bending of the plate which results locally in a change of curvature of the wall of the chamber 7. The bending of the wall of the chamber 7 causes in bending the part 8 of the body 1, namely the injection nozzle, with maximum displacement at its end 14 at the orifices 10.
Le déplacement généré à l'extrémité de la buse 14 permet d'expulser à travers chaque orifice 10 une micro-quantité de liquide qui donne naissance à une goutte 11 éjectée avec une certaine vitesse. Pour chaque cycle de tension électrique appliquée sur la plaquette piézo-électrique 6, celle-ci passe par deux états de déformation en flexion symétriques ce qui amène l'extrémité de la buse 14 à osciller entre deux positions symétriques E et F liées à une amplitude d'oscillation donnée. A chaque passage par l'un de ces points E ou F d'amplitude maximale se produit l'éjection des gouttes de carburant. Pour un cycle de tension on éjecte ainsi deux gouttes de carburant par orifice.The displacement generated at the end of the nozzle 14 makes it possible to expel through each orifice 10 a micro-quantity of liquid which gives rise to a drop 11 ejected with a certain speed. For each cycle of electric voltage applied to the piezoelectric plate 6, it passes through two symmetrical bending deformation states which causes the end of the nozzle 14 to oscillate between two symmetrical positions E and F linked to an amplitude given oscillation. At each passage through one of these points E or F of maximum amplitude, the fuel drops are ejected. For a tension cycle, two drops of fuel are ejected per orifice.
En faisant varier la valeur de la tension électrique appliquée entre les électrodes de la plaquette 6 on peut obtenir un effet de flexion du corps 7 plus ou moins important et régler ainsi la valeur de l'amplitude de l'oscillation à l'extrémité 14 de la buse. Ceci permet de faire varier la quantité de liquide éjecté par chaque orifice au cours du cycle d'oscillation et de faire ainsi varier le diamètre des gouttes éjectées. Chaque cycle de vibration produisant l'éjection d'un nombre déterminé de gouttes de carburant, on peut donc doser très précisément la quantité de carburant injecté en commandant électroniquement par le système de contrôle moteur la source de puissance électrique pour obtenir le nombre de cycles souhaités.
Entre les deux états de flexion de la chambre 7 qui provoque l'éjection du carburant hors des canaux 9, l'action des forces capillaires à 1 ' intérieur des canaux 9 permet d ' assurer leur remplissage en carburant de façon constante depuis le réservoir 4 jusqu'aux orifices 10.By varying the value of the electric voltage applied between the electrodes of the wafer 6, it is possible to obtain a more or less significant effect of bending of the body 7 and thus to adjust the value of the amplitude of the oscillation at the end 14 of the nozzle. This makes it possible to vary the quantity of liquid ejected by each orifice during the oscillation cycle and thus to vary the diameter of the ejected drops. Each vibration cycle producing the ejection of a determined number of drops of fuel, it is therefore possible to precisely dose the quantity of fuel injected by electronically controlling the source of electric power by the engine control system to obtain the desired number of cycles. . Between the two bending states of the chamber 7 which causes the fuel to be ejected from the channels 9, the action of the capillary forces inside the channels 9 makes it possible to ensure that they are constantly filled with fuel from the tank 4 to ports 10.
Ainsi, conformément à l'invention, l'éjection des gouttes à travers les orifices 10 à l'extrémité 14 de la buse 8 se fait par la seule action du mouvement oscillatoire en flexion de cette dernière. Mouvement oscillatoire en flexion, qui provoque d'une part une surpression locale dans le liquide au niveau de la buse et d'autre part une mise en mouvement du même liquide confiné dans la buse, les deux effets contribuants simultanément à la formation et à l'éjection des gouttes. Ainsi, c'est la vibration de l'extrémité 14 de la buse 8 qui fournit l'énergie cinétique nécessaire à l'éjection de la goutte.Thus, in accordance with the invention, the ejection of the drops through the orifices 10 at the end 14 of the nozzle 8 is effected by the sole action of the oscillatory movement in bending of the latter. Oscillating movement in bending, which causes on the one hand a local overpressure in the liquid at the level of the nozzle and on the other hand a setting in motion of the same liquid confined in the nozzle, the two effects contributing simultaneously to the formation and to the ejection of the drops. Thus, it is the vibration of the end 14 of the nozzle 8 which provides the kinetic energy necessary for the ejection of the drop.
La forme de l' injecteur 1 et plus particulièrement de la buse 8, est donc adaptée pour obtenir une amplification naturelle du mouvement . La structure en faisceau des canaux 9 répond parfaitement à cet objectif. De même, il est important que la structure retenue puisse atteindre des fréquences de résonance élevée permettant l'injection d'un nombre élevé de gouttes de carburant par seconde.The shape of the injector 1 and more particularly of the nozzle 8, is therefore suitable for obtaining a natural amplification of the movement. The beam structure of the channels 9 perfectly meets this objective. Likewise, it is important that the structure chosen can reach high resonant frequencies allowing the injection of a high number of drops of fuel per second.
L' injecteur selon l'invention fonctionne donc sans soupape puisque les canaux 9 débouchent librement à l'atmosphère, la rétention du liquide
dans la buse 8 s 'opérant simplement grâce à la tension superficielle du liquide et l'action des forces capillaires. Il se forme ainsi naturellement un ménisque liquide sur chaque orifice 10 de la buse 8, ménisque qui empêche l'écoulement de fluide tant que la différence de pression entre le liquide contenu dans la buse et 1 ' atmosphère environnant ne dépasse pas une valeur donnée.The injector according to the invention therefore operates without a valve since the channels 9 open freely to the atmosphere, the retention of the liquid in the nozzle 8 operating simply by virtue of the surface tension of the liquid and the action of the capillary forces. A liquid meniscus is thus naturally formed on each orifice 10 of the nozzle 8, a meniscus which prevents the flow of fluid as long as the pressure difference between the liquid contained in the nozzle and the surrounding atmosphere does not exceed a given value.
Cette différence de pression suffisamment faible dans le carburant entre les orifices 10 de la buse 8 et le réservoir tampon 4 situé en amont dans le corps de l' injecteur 1 est simplement obtenu grâce à la membrane 5 de mise à pression.This sufficiently low pressure difference in the fuel between the orifices 10 of the nozzle 8 and the buffer tank 4 located upstream in the body of the injector 1 is simply obtained by virtue of the diaphragm 5 for pressurizing.
Pour engendrer les déformations dans le corps de l' injecteur 1 ou au voisinage de la buse 8, on peut utiliser des matériaux piézo-électriques ou bien encore magnétostrictifs. Il suffit que ces matériaux se déforment sous l'influence d'un champ électrique ou magnétique et permettent donc l'application de contraintes générant les déformations voulues.To generate deformations in the body of the injector 1 or in the vicinity of the nozzle 8, it is possible to use piezoelectric materials or else magnetostrictive materials. It suffices that these materials deform under the influence of an electric or magnetic field and therefore allow the application of stresses generating the desired deformations.
A titre d'exemple, le dispositif d'injection comprend un corps 1 qui dans sa partie supportant la plaquette piézo-électrique 6 mesure 1 millimètre au total et environ 1 centimètre dans sa largeur et sa longueur, la buse a une longueur voisine de 20 millimètres et une épaisseur de l'ordre de 0,2 millimètre à son extrémité où est située une rangée d'orifices circulaires 10 de 30 microns de diamètre. On obtient alors l'éjection d'un double faisceau de gouttes avec des fréquences d'excitation allant de 40 kH à 400 kH, et ce pour
une tension alternative appliquée de l'ordre de 10 Volts crête. Le diamètre des gouttes est fonction de l'amplitude de la tension appliquée et de la fréquence de fonctionnement. La vitesse des gouttes selon le point de fonctionnement choisi varie de 5 à 15 mètres par seconde. Le temps de réponse du dispositif pour une mise en oscillation de la buse et l'éjection simultanée de gouttes de carburant est d'environ 10 microsecondes. Pour assurer un débit en carburant compatible avec le fonctionnement d'un moteur, un dispositif fonctionnant à 250 kH comporte 170 orifices 10 de 30 microns de diamètre à l'extrémité de la buse.By way of example, the injection device comprises a body 1 which in its part supporting the piezoelectric plate 6 measures 1 millimeter in total and about 1 centimeter in its width and its length, the nozzle has a length close to 20 millimeters and a thickness of the order of 0.2 millimeters at its end where is located a row of circular orifices 10 30 microns in diameter. We then obtain the ejection of a double beam of drops with excitation frequencies ranging from 40 kH to 400 kH, and this for an applied alternating voltage of the order of 10 volts peak. The diameter of the drops is a function of the amplitude of the applied voltage and the operating frequency. The speed of the drops depending on the operating point chosen varies from 5 to 15 meters per second. The response time of the device for an oscillation of the nozzle and the simultaneous ejection of drops of fuel is approximately 10 microseconds. To ensure a fuel flow compatible with the operation of an engine, a device operating at 250 kH has 170 orifices 10 of 30 microns in diameter at the end of the nozzle.
L' injecteur 1 selon l'invention indépendamment des avantages qu'il présente en matière de dosage et de vaporisation du carburant, grâce notamment à la calibration précise qu'il permet de la taille des gouttelettes, est par ailleurs particulièrement adapté pour opérer l'injection du carburant lors de la levée de la soupape d'admission 13 et injecter ainsi le carburant directement dans la chambre de combustion 15.The injector 1 according to the invention independently of the advantages which it presents in terms of metering and vaporization of the fuel, thanks in particular to the precise calibration which it allows for the size of the droplets, is moreover particularly suitable for operating the fuel injection when the intake valve 13 is lifted and thus inject the fuel directly into the combustion chamber 15.
Effet, lors de l'ouverture de la soupape d'admission 13, le flux d'air d'admission remplissant la chambre de combustion 15 a une vitesse d'environ 70 mètres par seconde au voisinage du col de la soupape. Ce flux assiste l'éjection de carburant et entraîne les gouttes qui sont éjectées en faisceau des orifices 10 pour les propulser directement dans la chambre 15 à travers l'ouverture de la soupape. La différence entre la vitesse d'éjection des gouttes, comprise entre 5 et
10 mètres par secondes et celle du flux d'air, provoque un phénomène d'abrasion des gouttes de carburant et contribue à leur évaporâtion.Effect, during the opening of the intake valve 13, the flow of intake air filling the combustion chamber 15 at a speed of about 70 meters per second in the vicinity of the neck of the valve. This flow assists the ejection of fuel and drives the drops which are ejected in a bundle of the orifices 10 to propel them directly into the chamber 15 through the opening of the valve. The difference between the ejection speed of the drops, between 5 and 10 meters per second and that of the air flow, causes abrasion of the fuel drops and contributes to their evaporation.
Bien entendu, l'invention n'est nullement limitée aux modes de réalisation décrits et illustrés qui n'ont été donnés qu'à titre d'exemple. Au contraire, l'invention comprend tous les équivalents techniques des moyens décrits ainsi que leurs combinaisons si celles-ci sont effectuées suivant son esprit.Of course, the invention is in no way limited to the embodiments described and illustrated which have been given only by way of example. On the contrary, the invention includes all the technical equivalents of the means described as well as their combinations if these are carried out according to the spirit.
Ainsi le corps 1 de l' injecteur peut ainsi être^ disposé plus près du col de la soupape 13 ou plus en amont dans le conduit d'admission 12, voir à l'extérieur du conduit d'admission dans un aménagement prévu dans la culasse, l'extrémité de la buse 8 débouchant dans le conduit d'admission 12 en un point situé soit, au voisinage du col de la soupape soit, plus en amont.Thus the body 1 of the injector can thus be placed closer to the neck of the valve 13 or more upstream in the intake duct 12, see outside of the intake duct in an arrangement provided in the cylinder head , the end of the nozzle 8 opening into the intake duct 12 at a point located either near the neck of the valve or further upstream.
Ainsi, selon différents modes de réalisation, les orifices d'injection peuvent être de forme circulaire, carré ou de toute autre forme géométrique, les dimensions transversales des orifices pouvant être réduites à quelques microns, par exemple de l'ordre de dix à trente microns. La section des orifices permet de calibrer la taille des gouttes formées, le calibrage de la taille des gouttes pouvant ensuite être modifiée en faisant varier l'amplitude d'oscillation de la buse.
Thus, according to different embodiments, the injection orifices can be circular, square or any other geometric shape, the transverse dimensions of the orifices being able to be reduced to a few microns, for example of the order of ten to thirty microns . The section of the orifices makes it possible to calibrate the size of the drops formed, the calibration of the size of the drops can then be modified by varying the amplitude of oscillation of the nozzle.
Claims
[1] Dispositif d'injection de carburant pour moteur à combustion interne comprenant un injecteur (1) relié à un circuit (2) d'alimentation en carburant sous une pression adaptée, ledit injecteur (1) comportant une buse d'injection (8) à l'extrémité (14) de laquelle est ménagé au moins un orifice d'injection de carburant (10), caractérisé en ce que ledit injecteur (1) coopère avec des moyens de mise en vibration cyclique (6) pilotés par le système électronique de contrôle moteur de façon à provoquer des oscillations mécaniques en flexion de la buse d'injection (8), ladite buse d'injection (8) étant adaptée pour éjecter une quantité de carburant prédéterminée à chacune de ses oscillations.[1] Fuel injection device for an internal combustion engine comprising an injector (1) connected to a fuel supply circuit (2) under a suitable pressure, said injector (1) comprising an injection nozzle (8 ) at the end (14) of which is provided at least one fuel injection orifice (10), characterized in that said injector (1) cooperates with cyclic vibration means (6) controlled by the system electronic engine control so as to cause mechanical oscillations in flexion of the injection nozzle (8), said injection nozzle (8) being adapted to eject a predetermined quantity of fuel at each of its oscillations.
[2] Dispositif d'injection de carburant selon la revendication 1, caractérisé en ce que ladite buse d'injection (8) est formée par une pluralité de canaux (9) de dimensions adaptées, réunis en faisceau.[2] Fuel injection device according to claim 1, characterized in that said injection nozzle (8) is formed by a plurality of channels (9) of suitable dimensions, joined in a bundle.
[3] Dispositif d'injection de carburant selon la revendication 2, caractérisé en ce que lesdits canaux sont adaptés pour être alimentés en carburant par capillarité.[3] Fuel injection device according to claim 2, characterized in that said channels are adapted to be supplied with fuel by capillary action.
[4] Dispositif d'injection de carburant selon la revendication 3, caractérisé en ce que lesdits canaux (9) présentent des orifices d'injection (10) adaptée pour éjecter le carburant sous forme de gouttelettes de tailles données.
[4] Fuel injection device according to claim 3, characterized in that said channels (9) have injection orifices (10) adapted to eject the fuel in the form of droplets of given sizes.
[5] Dispositif d'injection de carburant selon l'une quelconque des revendications 1 à 4, caractérisé en ce que ledit injecteur (1) présente une partie élastiquement déformable (7) qui coopère avec lesdits moyens de mise en vibration cyclique (6) pilotés par le système électronique de contrôle moteur, ladite buse d'injection (8) étant solidaire de cette partie déformable (7) .[5] Fuel injection device according to any one of claims 1 to 4, characterized in that said injector (1) has an elastically deformable part (7) which cooperates with said cyclic vibration means (6) controlled by the electronic engine control system, said injection nozzle (8) being integral with this deformable part (7).
[6] Dispositif d'injection de carburant selon la revendication 5, caractérisé en ce que ladite partie élastiquement déformable est formée par une chambre (7) s' étendant dans le prolongement d'un réservoir de carburant (4) auquel est connecté le circuit (2) d'alimentation en carburant par l'intermédiaire d'une vanne pilotée (3) dont l'ouverture est commandée en fonction du niveau de remplissage dudit réservoir (4) .[6] Fuel injection device according to claim 5, characterized in that said elastically deformable part is formed by a chamber (7) extending in the extension of a fuel tank (4) to which the circuit is connected (2) fuel supply via a pilot-operated valve (3) whose opening is controlled according to the filling level of said tank (4).
[7] Dispositif d'injection de carburant selon la revendication 6, caractérisé en ce que caractérisé en ce que ledit réservoir de carburant (4) coopère avec des moyens de régulation permettant d'ajuster la pression régnant dans ledit réservoir (4) à la pression régnant dans le circuit d'admission d'air (12) du moteur.[7] Fuel injection device according to claim 6, characterized in that said fuel tank (4) cooperates with regulating means making it possible to adjust the pressure prevailing in said tank (4) to the pressure prevailing in the air intake circuit (12) of the engine.
[8] Dispositif d'injection de carburant selon l'une quelconques des revendications 1 à 5, caractérisé en ce que lesdits moyens de mise en vibration sont formés par un actuateur piézoélectrique.
[8] Fuel injection device according to any one of claims 1 to 5, characterized in that said vibration means are formed by a piezoelectric actuator.
Applications Claiming Priority (3)
Application Number | Priority Date | Filing Date | Title |
---|---|---|---|
FR9705129A FR2762648B1 (en) | 1997-04-25 | 1997-04-25 | FUEL INJECTION DEVICE FOR INTERNAL COMBUSTION ENGINE |
FR9705129 | 1997-04-25 | ||
PCT/FR1998/000778 WO1998049443A1 (en) | 1997-04-25 | 1998-04-17 | Internal combustion engine fuel injecting device |
Publications (1)
Publication Number | Publication Date |
---|---|
EP0977946A1 true EP0977946A1 (en) | 2000-02-09 |
Family
ID=9506310
Family Applications (1)
Application Number | Title | Priority Date | Filing Date |
---|---|---|---|
EP98921556A Withdrawn EP0977946A1 (en) | 1997-04-25 | 1998-04-17 | Internal combustion engine fuel injecting device |
Country Status (3)
Country | Link |
---|---|
EP (1) | EP0977946A1 (en) |
FR (1) | FR2762648B1 (en) |
WO (1) | WO1998049443A1 (en) |
Families Citing this family (3)
Publication number | Priority date | Publication date | Assignee | Title |
---|---|---|---|---|
JP2003334479A (en) * | 2001-10-02 | 2003-11-25 | Ngk Insulators Ltd | Liquid jetting apparatus |
FR2879046B1 (en) | 2004-12-08 | 2007-10-26 | Renault Sas | METHOD FOR CONTROLLING A STEERING CIRCUIT FOR PIEZOSTRICTIVE OR MAGNOTOSTRICTIVE ACTUATORS |
DE102006026153A1 (en) * | 2006-06-06 | 2007-12-13 | Robert Bosch Gmbh | Spraying device for fluids |
Family Cites Families (4)
Publication number | Priority date | Publication date | Assignee | Title |
---|---|---|---|---|
DE2029207A1 (en) * | 1970-06-13 | 1971-12-16 | Daimler Benz Ag | Ultrasonic coupling transducer |
JPS59201962A (en) * | 1983-04-28 | 1984-11-15 | Matsushita Electric Ind Co Ltd | Atomizing apparatus |
DE3833093A1 (en) * | 1988-09-29 | 1990-04-12 | Siemens Ag | FUEL INJECTOR PROVIDED FOR INTERNAL COMBUSTION ENGINE WITH CONTROLLABLE CHARACTERISTICS OF THE FUEL JET |
US5437255A (en) * | 1994-03-15 | 1995-08-01 | Sadley; Mark L. | Fuel injection sytem employing solid-state injectors for liquid fueled combustion engines |
-
1997
- 1997-04-25 FR FR9705129A patent/FR2762648B1/en not_active Expired - Fee Related
-
1998
- 1998-04-17 WO PCT/FR1998/000778 patent/WO1998049443A1/en not_active Application Discontinuation
- 1998-04-17 EP EP98921556A patent/EP0977946A1/en not_active Withdrawn
Non-Patent Citations (1)
Title |
---|
See references of WO9849443A1 * |
Also Published As
Publication number | Publication date |
---|---|
WO1998049443A1 (en) | 1998-11-05 |
FR2762648B1 (en) | 1999-06-04 |
FR2762648A1 (en) | 1998-10-30 |
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