EP0323368A1 - Device for pneumatically injecting fuel - Google Patents

Device for pneumatically injecting fuel Download PDF

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Publication number
EP0323368A1
EP0323368A1 EP88403381A EP88403381A EP0323368A1 EP 0323368 A1 EP0323368 A1 EP 0323368A1 EP 88403381 A EP88403381 A EP 88403381A EP 88403381 A EP88403381 A EP 88403381A EP 0323368 A1 EP0323368 A1 EP 0323368A1
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EP
European Patent Office
Prior art keywords
cylinder
injection
valve
injector
chamber
Prior art date
Legal status (The legal status is an assumption and is not a legal conclusion. Google has not performed a legal analysis and makes no representation as to the accuracy of the status listed.)
Granted
Application number
EP88403381A
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German (de)
French (fr)
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EP0323368B1 (en
Inventor
Pierre Duret
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IFP Energies Nouvelles IFPEN
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IFP Energies Nouvelles IFPEN
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Publication of EP0323368A1 publication Critical patent/EP0323368A1/en
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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
    • F02M67/00—Apparatus in which fuel-injection is effected by means of high-pressure gas, the gas carrying the fuel into working cylinders of the engine, e.g. air-injection type
    • F02M67/02—Apparatus in which fuel-injection is effected by means of high-pressure gas, the gas carrying the fuel into working cylinders of the engine, e.g. air-injection type the gas being compressed air, e.g. compressed in pumps
    • F02M67/04—Apparatus in which fuel-injection is effected by means of high-pressure gas, the gas carrying the fuel into working cylinders of the engine, e.g. air-injection type the gas being compressed air, e.g. compressed in pumps the air being extracted from working cylinders of the engine

Definitions

  • the invention relates to a pneumatic fuel injection method in a cylinder of an internal combustion reciprocating engine and to a corresponding pneumatic injection device.
  • the introduction of fuel in spray form into the cylinder can be carried out by a pneumatic injection device comprising an injector opening into the cylinder provided with a valve controlled by a cam for its opening and closing, a supply means for the liquid fuel injector and a source of compressed air for spraying and injecting the fuel when the injector is opened.
  • the sweeping of the cylinder by fresh air is carried out by means of a pump casing communicating with the cylinder at its lower part, so that the piston moving in the cylinder produces a compression of the air of the casing by moving towards its bottom dead center.
  • Ducts joining the pump casing to the cylinder intake ports ensure the transfer of compressed air to the cylinder, this compressed air penetrating the cylinder which it scans when the intake lights are discovered by the piston during its movement towards are bottom dead center.
  • the pump housing can be connected to the injector by a conduit on which a valve is disposed.
  • the part of the duct located downstream of the valve can in itself constitute a compressed air capacity or be connected to such a capacity.
  • Such a device which makes it possible to avoid the use of an additional source of compressed gas however requires the provision of a connection conduit between the pump casing and the injector and possibly a capacity in communication with this conduit.
  • a source of auxiliary compressed air has always been used hitherto, or a connecting duct between the pump casing and the cylinder and possibly a compressed air storage capacity.
  • the object of the invention is therefore to propose a pneumatic fuel injection method in a cylinder of an alternating internal combustion engine comprising a cylinder in which a sweep is carried out independently with fresh non-fuel air and an injection of liquid fuel sprayed by a pressurized gas, at determined instants of the engine operating cycle, this process avoiding having to resort to the use of an auxiliary compressed air source and of means for establishing communication, in the case of an engine comprising a pump housing, this pump housing with the injector.
  • the spraying and injection of fuel into the cylinder are carried out by gases taken from a cylinder of the engine.
  • the invention also relates to a device for pneumatically injecting fuel into a cylinder of an engine, using gases taken from this cylinder or from another cylinder of the engine, in the case of an engine with several cylinders.
  • FIG. 1 we see a cylinder 1 of a two-stroke engine in which alternately moves a piston 2 connected via a connecting rod 3 to a crankshaft 4.
  • the cylinder 1 com provided by its open lower part with a pump casing 5 in which the piston 2 can partially penetrate its movement towards its bottom dead center, as shown in FIG. 1.
  • the casing 5 comprises an air intake pipe 7, the l opening and closing are controlled by a valve 6.
  • the piston 2, in its movement towards its bottom dead center, is capable of compressing the air contained in the casing 5 and of discharging it into conduits such as 8 opening out through transfer lights 9 in the cylinder chamber 1.
  • the scanning of the cylinder 1 with fresh air is thus ensured by virtue of the casing 5 and the conduits 8, when the piston 2 discovers the lights 9 by moving downwards.
  • An exhaust duct 11 communicates with the chamber of the cylinder 1 by exhaust lights 10 whose position, in the direction of the stroke of the piston 2, is slightly offset from the position of the transfer lights 9 so that the piston 2, moving downwards, first discovers the exhaust ports 10, then the transfer ports 9 which sweep the cylinder 1 in fresh air, the burnt gases being evacuated by the ports 10.
  • the cylinder 1 is closed at its upper part by a cylinder head 12 on which is fixed a spark plug 13 and an assembly 14 comprising a pneumatic injection device 15 and a capacity 17, this assembly allowing the implementation of the invention.
  • the pneumatic injection device which may be designated by "pneumatic injector 15" comprises an injector 16 for supplying liquid fuel.
  • the pneumatic injector 15 comprises a chamber 15a formed inside the cylinder head 12 opening into the upper part of the cylinder 1 at a valve seat 18 and a valve 20, the stem of which is in contact at its end with a actuating cam 21.
  • the valve 20 cooperates with the seat 18 to ensure the opening or closing of the pneumatic injector, by action of the cam 21 and of a return spring 22.
  • the fuel supply injector 16 supplies fuel to the chamber 15a.
  • This chamber 15a may comprise a venturi 24.
  • the capacity 17 communicates with the chamber of the injector 15a via a conduit 25. A part of this conduit can constitute a part of the chamber 15a itself and therefore comprise the feed injector 16 and the venturi 24.
  • the cam 21 opens the pneumatic injector 15 in pushing down the valve stem 20 as shown in FIG. 1.
  • the position in orientation of the cam 21 on its shaft 21a can be adjusted to obtain an opening for an angle ⁇ of a chosen value, that is i.e. for a well-defined position of the piston 2.
  • the chamber 15a of the injector 15 has been previously filled with liquid fuel by the fuel supply injector 16, so that this liquid fuel is sprayed very finely by the gas at very high speed and injected into the cylinder 1, at the level of the seat 18, in the form of jets 26 constituted by gas containing in suspension very fine droplets of fuel and possibly mixed with vaporized fuel, in the case where the capacity 17 contains hot gases.
  • the mixture of gas and fuel in spray form mixes with the fresh air filling the cylinder 1 then the mixture of carburetted air thus obtained is compressed by the piston 2, when the latter has moved upwards in the cylinder 1, so as to mask the lights 9 and 10.
  • the shape of the cam 21 is intended to keep the valve 20 open during the start of compression.
  • the pressure of the carburetted air in the cylinder increases to a level higher than the pressure in capacity 17. Air or carburetted air, depending on how the injection is adjusted and according to the stratification of the fresh air and the carburetted air in the cylinder 1 enters the capacity 17, the recharging of pressurized gas is thus ensured.
  • the cam 21 has a shape and a position making it possible to allow the valve 20 to close under the action of the spring 22, at a well-determined moment when the mixture is compressed in the cylinder 1, so that the pressure of the gases in the chamber 17 in equilibrium with the cylinder chamber 1 makes it possible to carry out, during the following cycle, an efficient spraying and injection of fuel into the cylinder.
  • the shape of the cam 21 can be designed so that the valve 20 closes between 100 ° and 130 ° after the bottom dead center.
  • the engine operating cycle normally continues with the ignition and combustion of the fuel mixture, when the piston is at its top dead center.
  • the piston 2 then descends back into the cylinder, the exhaust of the burnt gases and the sweeping of fresh air from the cylinder again occur as described above.
  • a new fuel injection using the pressurized gases of capacity 17 which was recharged during the previous cycle then takes place A.
  • the disadvantage of the operating mode which has been described is that the capacity 17 is recharged with gases containing fuel, so that the efficiency of the engine undergoes a slight decrease compared to an operation using a source of compressed air whose reloading is not performed from the engine cylinder.
  • the cam 21 is such that the valve 20 first opens shortly after the cylinder has reached its bottom dead center, so that a pneumatic injection is carried out as described above thanks to the pressurized gas contained in the capacity 17.
  • the cam 21 of complex shape also allows a second opening of the valve 20 during the expansion phase or even during the exhaust phase of the burnt gases filling the cylinder 1, at a time when the pressure in the cylinder is greater than the pressure in the capacity 17.
  • the capacity 17 is therefore recharged by gases which are largely burnt gases or gases containing a small residual amount of unburned fuel.
  • the cam 21 allows the valve 20 to close a first time, after injection, at the start of compression in the cylinder, before the pressure of the carburetted air is sufficient for this air to enter the capacity 17
  • the valve 20 then remains closed during all of the compression, combustion and the start of expansion.
  • the valve 20 then opens during expansion or at the start of the exhaust, for a time and with a lower lift than when the first opening. Indeed, the pressure difference between the chamber of the cylinder 1 and the capacity 17 is then much higher than during the first opening ensuring the injection of the fuel mixture.
  • the capacity 17 is therefore put under pressure very quickly by the gases contained in the chamber of the cylinder 1.
  • the injector 16 it is possible to carry out by the injector 16 a discontinuous injection so that the latter does not inject fuel when the filling of the capacity is in progress.
  • a simple way to obtain such operation is to operate the injector 16 only when the valve 20 is closed.
  • FIGs 2 and 3 there is shown the upper part of a cylinder 30 of a two-stroke engine as described above comprising an injection device 31 in its upper part produced in a form different from that of the device 14 shown in Figure 1.
  • the pneumatic injector 32 opening into the upper part of the cylinder 30 comprises, as previously, a valve 33 controlled by a cam 34, a means for supplying liquid fuel not shown and a device 35 supplying the pneumatic injector 32 with gas under pressure allowing spraying and injection of liquid fuel.
  • the device 35 comprises a conduit 36 communicating, at one of its ends, with the cylinder chamber 30 by a light 37 arranged above the exhaust and transfer ports of the cylinder not shown and at its other end, with the pneumatic injector chamber 32 at the top of the cylinder.
  • a valve 38 is disposed on the pipe 36 and delimits on this pipe an upstream part communicating with the cylinder 30 and a downstream part communicating with the injector 32. The valve 38 opens when the differential pressure between the upstream and the downstream in the conduit 36 exceeds a certain value corresponding to the tare weight of the valve 38.
  • the downstream part of the duct 36 is capable of constituting by itself a capacity of pressurized gas in communication with the valve chamber 32. This downstream part of the duct 36 can also be put in communication with a capacity allowing the storage of gas under pressure.
  • the piston 30a moves upwards inside the cylinder 30 and carries out the compression of a fuel mixture located in the upper part of the cylinder.
  • the piston 30a masks the light 37 and the valve 38 which is subjected to slightly different upstream and downstream pressures remain closed.
  • the operating cycle of the engine is represented in the form of a hatched surface in a pressure diagram of the gases contained in the cylinder as a function of the volume occupied by these gases.
  • the engine operating point describes the curve 40 delimiting the cycle at its lower part when the piston moves up and the upper limit curve 41 of the cycle when the piston 30a moves down.
  • the piston 30a reaching its top dead center, the volume V is minimum.
  • the ignition following combustion occurs during compression.
  • the pressure in the cylinder reaches soon after its maximum and the piston moves down.
  • the volume of the gases in the cylinder has a value V0 and the pressure of these gases, a value P2.
  • the engine operating point corresponds to point A in FIG. 4.
  • the valve 38 lifts and the gases contained in the cylinder chamber 30 fill the entire duct 35 possibly including a storage capacity for pressurized gas downstream valve 38.
  • downstream part of the conduit 35 is, when the apertures 37 are opened, at a pressure below P2.
  • the piston 30a continues to move downwards and discovers the exhaust ports.
  • the pressure decreases in the cylinder chamber during the exhaust and sweeping phases with fresh air.
  • the valve 38 closes very quickly as soon as the pressure is less than P2. Closing the valve 38 therefore ensures the constitution of a gas reserve at a pressure substantially equal to P2.
  • the cam 34 controls the opening of the valve 33 of the injector 32 (operating point I). Liquid fuel is sprayed and injected into the upper part of the cylinder 30 by the pressure gas P2 retained in the duct 35 and / or the storage capacity, downstream of the valve 38.
  • the pneumatic injector can be designed to close sufficiently quickly, this being determined during the design or the development of the engine by the law of the cam 34, the pressure downstream of the valve 38 is established at a value less than P2.
  • the fuel mixture contained in the cylinder is then compressed by the piston 30a.
  • the upper part of the piston 30a masks the opening 37 at the start of the compression (point B in FIG. 4).
  • the residual volume in the cylinder is V0 and the gas pressure P1.
  • the pressure P1 as can be seen in the diagram in FIG. 4, is notably lower than the pressure P2.
  • the pressure in the conduit 35 upstream of the valve 38 therefore becomes established at the value P1 ⁇ P2. This position of the piston 30a is shown in FIG. 2.
  • the conditions of the injection are such that the pressure downstream of the valve 38 is established at a value P3 between P2 and P1.
  • valve 38 opens or vre during compression to allow the conduit 36 to reach a pressure close to P1 at the time when the rise of the piston masks the light 37.
  • the sequence takes place identically in both cases.
  • valve 38 therefore remains closed until the point of operation returns to A (configuration of Figure 3).
  • the piston 30a discovers the light 37, so that the upstream part of the conduit 35 is brought to pressure P2> P3.
  • the valve 38 opens and the downstream part of the conduit 35 constituting the injection gas reserve capacity is recharged with burnt gases at pressure P2.
  • a pneumatic injection device 42 is associated with the cylinder 40C and comprises a pneumatic injector, the chamber of which opens into the upper part of the cylinder 40C at the level of a seat with which the valve 43 of the injector is associated.
  • the injection device 42 also comprises a means for supplying the pneumatic injector with liquid fuel, not shown, and a conduit 45 joining the upper part of the chamber of the cylinder 41C to the chamber of the pneumatic injector 42 of the cylinder 40C.
  • the two cylinders 40C and 41C are chosen so as to present an offset in their operating cycle such that at the end of the sweep and before the compression in the cylinder 40C, at the moment when the pneumatic injection of fuel will be controlled by opening of the valve 43, the piston 41a of the cylinder 41 in the expansion phase discovers the light 44 making the conduit 45 communicate with the combustion chamber of the cylinder 41C.
  • the gases in cylinder 41C are then at a pressure much higher than the pressure of the gases in the cylinder 40C, so that at the opening of the valve 43 the spraying and the injection of the fuel into the cylinder 40C are ensured by the pressurized gases of the 41C cylinder chamber.
  • FIG. 5 shows the configuration of the cylinders 40C and 41C, just before the injection of fuel into the cylinder 40C, when the lumen 44 of the cylinder 41C is unmasked by the piston 41a moving downwards.
  • the cylinder 41C includes a fuel injection device 46 similar to the device 42 of the cylinder 40C, the conduit 47 for admission of pressurized gas being connected to an engine cylinder having an offset in its operating cycle relative to the cylinder 41C analogous to the offset existing between the cylinders 40C and 41C.
  • FIG. 6 there is shown an alternative embodiment of the injection device 32 shown in Figures 2 and 3.
  • the corresponding elements in Figures 2 and 3 on the one hand and 6 on the other hand have the same references with the exponent ′ as regards the elements of the device shown in FIG. 6.
  • the injection device 32 ′ comprises a conduit 36 ′ similar to the conduit 36 of the device shown in FIGS. 2 and 3 communicating, at one of its ends by a light 37 ′, with the interior chamber of the cylinder 30 ′ and at its other end, with the injector chamber communicating via the valve 33 ′, with the upper part of the cylinder 30 ′.
  • a valve 38 ′ is interposed on the conduit 36 ′ and separates this conduit 36 ′ into a upstream part communicating with the light 37 ′ of the cylinder 30 ′ and a downstream part communicating with the pneumatic injector.
  • the conduit 36 ′ is connected by means of a conduit 50 and a valve 51 with a source of fresh air which can be constituted by atmospheric air, the valve 51 having its entry into the open air.
  • the chamber of this cylinder 30 ′ can be depressed by the effects of the exhaust wave. This vacuum causes the valve 51 to open and the upstream portion of the duct 36 ′ to sweep through the cylinder 30 with fresh air.
  • the method and the device according to the invention have in all cases the advantage of using, for spraying and injecting fuel, pressurized gas available in the engine itself.
  • This pressurized gas can also be taken near the place where it is used for injecting fuel into the cylinder.
  • Gas pressures can also be very high compared to the pressure in the cylinder at the time of injection, which improves the quality of the fuel spraying and injection.
  • injectors of different shapes of capacities for storing pressurized gases in disposi various tions with respect to the injector and to the cylinders and control cams of the injector of various shapes.
  • the invention applies not only to two-stroke engines but also to any internal combustion internal engine in which an introduction and a sweep of fresh air and a pneumatic fuel injection are carried out independently.
  • valve 20 33, 43, 46 or 33 ′ an automatic valve operating as a valve, a rotating plug or an electromagnetically controlled valve.

Abstract

Flushing by fresh, petrol-free air and injection of liquid fuel atomised by pressurised gas are performed independently in the engine cylinder (1) at predetermined points in the operating cycle of the engine. The atomisation and injection of the fuel into the cylinder (1) are achieved by gases drawn from the engine cylinder (1). The injection device may comprise a volume (17) in which the gases drawn from the cylinder (1) are stored. The drawing of gases from the cylinder (1) may be performed by way of the pneumatic injector (15), when the valve (20) opens. …<IMAGE>…

Description

L'invention concerne un procédé d'injection pneumatique de carburant dans un cylindre d'un moteur alternatif à combustion interne et un dispositif d'in­jection pneumatique correspondant.The invention relates to a pneumatic fuel injection method in a cylinder of an internal combustion reciprocating engine and to a corresponding pneumatic injection device.

Dans les moteurs à deux temps à un ou plu­sieurs cylindres, à haut rendement on cherche à réa­liser de façon indépendante, un balayage du ou des cy­lindres par de l'air frais non carburé et une intro­duction de carburant liquide sous forme pulvérisée dans le ou les cylindres, ces deux opérations étant effectuées à des instants successifs et bien détermi­nés du cycle de fonctionnement du moteur.In two-stroke engines with one or more cylinders, with high efficiency, it is sought to carry out independently, a sweeping of the cylinder (s) with fresh non-carburized air and an introduction of liquid fuel in spray form into the cylinders, these two operations being carried out at successive and well-defined instants of the engine operating cycle.

L'introduction de carburant sous forme pul­vérisée dans le cylindre peut être réalisée par un dispositif d'injection pneumatique comportant un in­jecteur débouchant dans le cylindre muni d'une soupape commandée par une came pour son ouverture et sa ferme­ture, un moyen d'alimentation de l'injecteur en carbu­rant liquide et une source d'air comprimé assurant la pulvérisation et l'injection du carburant au moment de l'ouverture de l'injecteur.The introduction of fuel in spray form into the cylinder can be carried out by a pneumatic injection device comprising an injector opening into the cylinder provided with a valve controlled by a cam for its opening and closing, a supply means for the liquid fuel injector and a source of compressed air for spraying and injecting the fuel when the injector is opened.

Le balayage du cylindre par de l'air frais est réalisé grâce à un carter pompe communiquant avec le cylindre à sa partie inférieure, de façon que le piston se déplaçant dans le cylindre produise une compression de l'air du carter en se déplaçant vers son point mort bas. Des conduits joignant le carter pompe à des lumières d'admission du cylindre assurent le transfert de l'air comprimé vers le cylindre, cet air comprimé pénétrant dans le cylindre dont il réali­se le balayage, lorsque les lumières d'admission sont découvertes par le piston au cours de son déplacement vers sont point mort bas.The sweeping of the cylinder by fresh air is carried out by means of a pump casing communicating with the cylinder at its lower part, so that the piston moving in the cylinder produces a compression of the air of the casing by moving towards its bottom dead center. Ducts joining the pump casing to the cylinder intake ports ensure the transfer of compressed air to the cylinder, this compressed air penetrating the cylinder which it scans when the intake lights are discovered by the piston during its movement towards are bottom dead center.

On a proposé de réaliser l'injection pneuma­tique du carburant en utilisant l'air comprimé du car­ter pompe pour effectuer la pulvérisation et l'injec­tion du carburant. A cette fin, le carter pompe peut être relié à l'injecteur par un conduit sur lequel est disposé un clapet. La partie du conduit située en aval du clapet peut constituer en elle-même une capacité d'air comprimé ou être reliée à une telle capacité. Lors de l'ouverture de l'injecteur, une certaine quan­tité d'air comprimé est utilisée pour pulvériser le carburant et l'injecteur dans le cylindre. Le recharge­ment de la capacité en air comprimé est réalisé, lors­que la pression est voisine de son maximum dans le carter pompe, par ouverture du clapet.It has been proposed to perform pneumatic fuel injection using compressed air from the pump housing to perform the fuel spraying and injection. To this end, the pump housing can be connected to the injector by a conduit on which a valve is disposed. The part of the duct located downstream of the valve can in itself constitute a compressed air capacity or be connected to such a capacity. When opening the injector, a certain amount of compressed air is used to spray the fuel and the injector into the cylinder. The recharging of the compressed air capacity is carried out, when the pressure is close to its maximum in the pump casing, by opening the valve.

Un tel dispositif qui permet d'éviter l'uti­lisation d'une source annexe de gaz comprimé nécessite cependant de prévoir un conduit de jonction entre le carter pompe et l'injecteur et éventuellement une ca­pacité en communication avec ce conduit.Such a device which makes it possible to avoid the use of an additional source of compressed gas however requires the provision of a connection conduit between the pump casing and the injector and possibly a capacity in communication with this conduit.

Dans le cas des moteurs à injection à plu­sieurs cylindres, on a proposé d'utiliser les gaz chauds sous pression prélevés dans un cylindre pour réaliser la pulvérisation du carburant dans un autre cylindre du moteur. L'injection est réalisée au niveau de la soupape d'admission du cylindre par laquelle est aspiré l'air carburé destiné à remplir le cylindre. L'effet des gaz chauds prélevés se limite à assurer la pulvérisation et éventuellement la vaporisation du carburant liquide dont l'introduction dans le cylindre est assurée au moment de l'ouverture de la soupape d'admission, par mélange avec l'air admis et aspira­tion.In the case of injection engines with several cylinders, it has been proposed to use the hot pressurized gases taken from a cylinder to spray the fuel into another cylinder of the engine. The injection is carried out at the level of the cylinder intake valve through which the carburetted air intended to fill the cylinder is sucked. The effect of the hot gases sampled is limited to spraying and possibly vaporizing the liquid fuel, the introduction of which into the cylinder is ensured at the time of the opening of the intake valve, by mixing with the intake air and aspiration.

Dans ce cas, contrairement au cas des mo­teurs à deux temps et analogues, il n' y a pas d'in­ troduction d'air frais de balayage dans le cylindre indépendamment de l'introduction de carburant et cette introduction de carburant n'est pas effectuée sous pression et par un injecteur pneumatique indépendant du dispositif d'introduction d'air dans le cylindre.In this case, unlike the case of two-stroke engines and the like, there is no in supply of fresh sweeping air into the cylinder independently of the introduction of fuel and this introduction of fuel is not carried out under pressure and by a pneumatic injector independent of the device for introducing air into the cylinder.

Dans le cas de l'injection pneumatique, on a toujours utilisé jusqu'ici soit une source d'air com­primé auxiliare, soit un conduit de liaison entre le carter pompe et le cylindre et éventuellement une ca­pacité de stockage d'air comprimé.In the case of pneumatic injection, a source of auxiliary compressed air has always been used hitherto, or a connecting duct between the pump casing and the cylinder and possibly a compressed air storage capacity.

Le but de l'invention est donc de proposer un procédé d'injection pneumatique de carburant dans un cylindre d'un moteur alternatif à combustion inter­ne comportant un cylindre dans lequel on réalise in­dépendamment un balayage par de l'air frais non carbu­ré et une injection de carburant liquide pulvérisé par un gaz sous pression, à des instants déterminés du cy­cle de fonctionnement du moteur, ce procédé évitant de recourir à l'utilisation d'une source d'air comprimé auxiliare et de moyens pour mettre en communication, dans le cas d'un moteur comportant un carter pompe, ce carter pompe avec l'injecteur.The object of the invention is therefore to propose a pneumatic fuel injection method in a cylinder of an alternating internal combustion engine comprising a cylinder in which a sweep is carried out independently with fresh non-fuel air and an injection of liquid fuel sprayed by a pressurized gas, at determined instants of the engine operating cycle, this process avoiding having to resort to the use of an auxiliary compressed air source and of means for establishing communication, in the case of an engine comprising a pump housing, this pump housing with the injector.

Dans ce but, la pulvérisation et l'injection du carburant dans le cylindre sont réalisés par des gaz prélevés dans un cylindre du moteur.For this purpose, the spraying and injection of fuel into the cylinder are carried out by gases taken from a cylinder of the engine.

L'invention est également relative à un dis­positif pour réaliser l'injection pneumatique de car­burant dans un cylindre d'un moteur, en utilisant des gaz prélevés dans ce cylindre ou dans un autre cylin­dre du moteur, dans le cas d'un moteur à plusieurs cy­lindres.The invention also relates to a device for pneumatically injecting fuel into a cylinder of an engine, using gases taken from this cylinder or from another cylinder of the engine, in the case of an engine with several cylinders.

Afin de bien faire comprendre l'invention, on va maintenant décrire, à titre d'exemple non limi­tatif, en se référant aux figures jointes en annexe, la mise en oeuvre de procédé suivant l'invention, sui­vant plusieurs variantes et en utilisant des disposi­tifs d'injection suivant plusieurs modes de réalisa­tion.

  • La figure 1 est une vue schématique en élé­vation et en coupe d'un moteur à deux temps comportant un dispositif d'injection pneumatique suivant un pre­mier mode de réalisation permettant la mise en oeuvre de l'invention.
  • La figure 2 est une vue partielle en éléva­tion et en coupe d'un cylindre d'un moteur comportant un dispositif d'injection pneumatique suivant un se­cond mode de réalisation permettant la mise en oeuvre de l'invention.
  • La figure 3 est une vue analogue à la figure 2 montrant le cylindre du moteur à un instant diffé­rent du cycle de fonctionnement.
  • La figure 4 est un diagramme de fonctionne­ment du moteur dont le cylindre est représenté sur les figures 2 et 3.
  • La figure 5 est une vue schématique en élé­vation et en coupe de deux cylindres d'un moteur mul­ticylindres comportant un dispositif d'injection sui­vant un troisième mode de réalisation, permettant la mise en oeuvre de l'invention.
  • La figure 6 est une vue schématique en coupe et en élévation d'un cylindre d'un moteur comportant un dispositif d'injection suivant un quatrième mode de réalisation, permettant la mise en oeuvre de l'inven­tion.
In order to clearly understand the invention, a description will now be given, by way of nonlimiting example, with reference to the attached figures, implementing the method according to the invention, according to several variants and using injection devices according to several embodiments.
  • Figure 1 is a schematic elevational view in section of a two-stroke engine comprising a pneumatic injection device according to a first embodiment allowing the implementation of the invention.
  • FIG. 2 is a partial view in elevation and in section of a cylinder of an engine comprising a pneumatic injection device according to a second embodiment allowing the implementation of the invention.
  • Figure 3 is a view similar to Figure 2 showing the engine cylinder at a different time from the operating cycle.
  • FIG. 4 is an operating diagram of the engine, the cylinder of which is shown in FIGS. 2 and 3.
  • Figure 5 is a schematic elevational view in section of two cylinders of a multi-cylinder engine having an injection device according to a third embodiment, allowing the implementation of the invention.
  • Figure 6 is a schematic sectional view in elevation of a cylinder of an engine comprising an injection device according to a fourth embodiment, allowing the implementation of the invention.

Sur la figure 1, on voir un cylindre 1 d'un moteur à deux temps dans lequel se déplace de manière alternative un piston 2 relié par l'intermédiaire d'une bielle 3 à un vilebrequin 4. Le cylindre 1 com­ munique par sa partie inférieure ouverte avec un car­ter pompe 5 dans lequel le piston 2 peut pénétrer par­tiellement dans son déplacement vers son point mort bas, comme représenté sur la figure 1. Le carter 5 comporte une conduite d'admission d'air 7 dont l'ou­verture et la fermeture sont commandées par un clapet 6. Le piston 2, dans son déplacement vers son point mort bas, est susceptible de comprimer l'air contenu dans le carter 5 et de le refouler dans des conduits tels que 8 débouchant par des lumières de transfert 9 dans la chambre du cylindre 1. Le balayage du cylindre 1 par de l'air frais est ainsi assuré grâce au carter 5 et aux conduits 8, lorsque le piston 2 découvre les lumières 9 en se déplaçant vers le bas.In Figure 1, we see a cylinder 1 of a two-stroke engine in which alternately moves a piston 2 connected via a connecting rod 3 to a crankshaft 4. The cylinder 1 com provided by its open lower part with a pump casing 5 in which the piston 2 can partially penetrate its movement towards its bottom dead center, as shown in FIG. 1. The casing 5 comprises an air intake pipe 7, the l opening and closing are controlled by a valve 6. The piston 2, in its movement towards its bottom dead center, is capable of compressing the air contained in the casing 5 and of discharging it into conduits such as 8 opening out through transfer lights 9 in the cylinder chamber 1. The scanning of the cylinder 1 with fresh air is thus ensured by virtue of the casing 5 and the conduits 8, when the piston 2 discovers the lights 9 by moving downwards.

Un conduit d'échappement 11 communique avec la chambre du cylindre 1 par des lumières d'échappe­ment 10 dont la position, dans la direction de la course du piston 2, est légèrement décalée par rapport à la position des lumières de transfert 9 de façon que le piston 2 en se déplaçant vers le bas découvre d'abord les lumières d'échappement 10, puis les lumiè­res de transfert 9 qui assurent le balayage du cylin­dre 1 en air frais, les gaz brûlés étant évacués par les lumières 10.An exhaust duct 11 communicates with the chamber of the cylinder 1 by exhaust lights 10 whose position, in the direction of the stroke of the piston 2, is slightly offset from the position of the transfer lights 9 so that the piston 2, moving downwards, first discovers the exhaust ports 10, then the transfer ports 9 which sweep the cylinder 1 in fresh air, the burnt gases being evacuated by the ports 10.

Le cylindre 1 est fermé à sa partie supé­rieure par une culasse 12 sur laquelle est fixée une bougie d'allumage 13 et un ensemble 14 comportant un dispositif d'injection pneumatique 15 et une capacité 17, cet ensemble permettant la mise en oeuvre de l'in­vention.The cylinder 1 is closed at its upper part by a cylinder head 12 on which is fixed a spark plug 13 and an assembly 14 comprising a pneumatic injection device 15 and a capacity 17, this assembly allowing the implementation of the invention.

Le dispositif d'injection pneumatique qui pourra être désigné par "injecteur pneumatique 15" comporte un injecteur 16 d'alimentation en carburant liquide.The pneumatic injection device which may be designated by "pneumatic injector 15" comprises an injector 16 for supplying liquid fuel.

L'injecteur pneumatique 15 comporte une chambre 15a ménagée à l'intérieur de la culasse 12 débouchant dans la partie supérieure du cylindre 1 au niveau d'un siège de soupape 18 et une soupape 20 dont la tige est en contact à son extrémité avec une came d'actionnement 21.The pneumatic injector 15 comprises a chamber 15a formed inside the cylinder head 12 opening into the upper part of the cylinder 1 at a valve seat 18 and a valve 20, the stem of which is in contact at its end with a actuating cam 21.

La soupape 20 coopère avec le siège 18 pour assurer l'ouverture ou la fermeture de l'injecteur pneumatique, par action de la came 21 et d'un ressort de rappel 22.The valve 20 cooperates with the seat 18 to ensure the opening or closing of the pneumatic injector, by action of the cam 21 and of a return spring 22.

L'injecteur d'alimentation en carburant 16 fournit de carburant à la chambre 15a. Cette chambre 15a peut comporter un venturi 24. La capacité 17 com­munique avec la chambre de l'injecteur 15a par l'in­termédiaire d'un conduit 25. Une partie de ce conduit peut constituer une partie de la chambre 15a elle-même et donc comporter l'injecteur d'alimentation 16 et le venturi 24.The fuel supply injector 16 supplies fuel to the chamber 15a. This chamber 15a may comprise a venturi 24. The capacity 17 communicates with the chamber of the injector 15a via a conduit 25. A part of this conduit can constitute a part of the chamber 15a itself and therefore comprise the feed injector 16 and the venturi 24.

Lorsque le piston 2 se déplace vers le bas, il découvre successivement les ouvertures d'échappe­ment 10 et les ouvertures de transfert 9 avant de par­venir à son point mort bas, comme expliqué plus haut. Le balayage du cylindre en air frais se poursuit et le piston 2 parvient à son point mort bas puis se déplace vers le haut comme représenté sur la figure 1.When the piston 2 moves downwards, it successively discovers the exhaust openings 10 and the transfer openings 9 before reaching its bottom dead center, as explained above. The scanning of the cylinder in fresh air continues and the piston 2 reaches its bottom dead center and then moves upwards as shown in FIG. 1.

Lorsque le vilebrequin a effectué une rota­tion d'un angle α qui peut être compris entre 10 et 50° après le point mort bas et de préférence entre 20° et 30°, la came 21 réalise l'ouverture de l'injecteur pneumatique 15 en poussant vers le bas la tige de la soupape 20 comme représenté sur la figure 1. La position en orientation de la came 21 sur son arbre 21a peut être réglée pour obtenir une ouverture pour un angle α d'une valeur choisie, c'est-à-dire pour une position bien déterminée du piston 2.When the crankshaft has made a rotation of an angle α which can be between 10 and 50 ° after the bottom dead center and preferably between 20 ° and 30 °, the cam 21 opens the pneumatic injector 15 in pushing down the valve stem 20 as shown in FIG. 1. The position in orientation of the cam 21 on its shaft 21a can be adjusted to obtain an opening for an angle α of a chosen value, that is i.e. for a well-defined position of the piston 2.

Du gaz contenu dans la capacité 17 dont la pression intérieure est sensiblement supérieure à la pression dans le cylindre au moment choisi pour l'in­jection pénètre à très grande vitesse dans la chambre de l'injecteur pneumatique 15 après traversée du ven­turi 24.Gas contained in the capacity 17 whose internal pressure is substantially higher than the pressure in the cylinder at the time chosen for injection penetrates at very high speed into the chamber of the pneumatic injector 15 after passing through the venturi 24.

La chambre 15a de l'injecteur 15 a été rem­plie préalablement de carburant liquide par l'injec­teur d'alimentation en carburant 16, si bien que ce carburant liquide est pulvérisé très finement par le gaz à très grande vitesse et injecté dans le cylindre 1, au niveau du siège 18, sous forme de jets 26 cons­titués par du gaz contenant en suspension de très fi­nes gouttelettes de carburant et éventuellement mélan­gé à du carburant vaporisé, dans le cas où la capacité 17 renferme des gaz chauds.The chamber 15a of the injector 15 has been previously filled with liquid fuel by the fuel supply injector 16, so that this liquid fuel is sprayed very finely by the gas at very high speed and injected into the cylinder 1, at the level of the seat 18, in the form of jets 26 constituted by gas containing in suspension very fine droplets of fuel and possibly mixed with vaporized fuel, in the case where the capacity 17 contains hot gases.

Le mélange de gaz et de carburant sous forme pulvérisée se mélange à l'air frais remplissant le cy­lindre 1 puis le mélange d'air carburé ainsi obtenu est comprimé par le piston 2, lorsque celui-ci s'est déplacé vers le haut dans le cylindre 1, de façon à masquer les lumières 9 et 10.The mixture of gas and fuel in spray form mixes with the fresh air filling the cylinder 1 then the mixture of carburetted air thus obtained is compressed by the piston 2, when the latter has moved upwards in the cylinder 1, so as to mask the lights 9 and 10.

La forme de la came 21 est prévue pour main­tenir la soupape 20 ouverte pendant le début de la compression. La pression de l'air carburé dans le cy­lindre augmente jusqu'à un niveau supérieur à la pres­sion dans la capacité 17. De l'air ou de l'air carbu­ré, suivant la façon dont est réglée l'injection et suivant la stratification de l'air frais et de l'air carburé dans le cylindre 1, pénètre dans la capacité 17 dont le rechargement en gaz sous pression est ainsi assuré.The shape of the cam 21 is intended to keep the valve 20 open during the start of compression. The pressure of the carburetted air in the cylinder increases to a level higher than the pressure in capacity 17. Air or carburetted air, depending on how the injection is adjusted and according to the stratification of the fresh air and the carburetted air in the cylinder 1 enters the capacity 17, the recharging of pressurized gas is thus ensured.

Dans le cas où de l'air carburé est refoulé dans la capacité 17 pour son rechargement, cet air carburé renferme bien évidemment une proportion de carburant bien inférieure à la proportion de carburant contenu dans le mélange injecté.In the case where carburetted air is discharged into capacity 17 for its recharging, this air fuel obviously contains a much lower proportion of fuel than the proportion of fuel contained in the injected mixture.

La came 21 a une forme et une position per­mettant de laisser se refermer la soupape 20 sous l'action du ressort 22, à un moment bien déterminé lors de la compression du mélange dans le cylindre 1, de façon que la pression des gaz dans la chambre 17 en équilibre avec la chambre du cylindre 1 permette de réaliser, au cours du cycle suivant, une pulvérisation et une injection efficaces du carburant dans le cylin­dre.The cam 21 has a shape and a position making it possible to allow the valve 20 to close under the action of the spring 22, at a well-determined moment when the mixture is compressed in the cylinder 1, so that the pressure of the gases in the chamber 17 in equilibrium with the cylinder chamber 1 makes it possible to carry out, during the following cycle, an efficient spraying and injection of fuel into the cylinder.

La forme de la came 21 pourra être dessinée pour que la soupape 20 se referme entre 100° et 130° après le point mort bas.The shape of the cam 21 can be designed so that the valve 20 closes between 100 ° and 130 ° after the bottom dead center.

Le cycle de fonctionnement du moteur se poursuit normalement par l'allumage et la combustion du mélange carburé, lorsque le piston est à son point mort haut. Le piston 2 redescend ensuite dans le cy­lindre, l'échappement des gaz brûlés et le balayage en air frais du cylindre se produisent à nouveau comme décrit ci-dessus. Une nouvelle injection de carburant utilisant les gaz sous pression de la capacité 17 qui a été rechargée au cours du cycle précédent a alors lieu A.The engine operating cycle normally continues with the ignition and combustion of the fuel mixture, when the piston is at its top dead center. The piston 2 then descends back into the cylinder, the exhaust of the burnt gases and the sweeping of fresh air from the cylinder again occur as described above. A new fuel injection using the pressurized gases of capacity 17 which was recharged during the previous cycle then takes place A.

L'inconvénient du mode de fonctionnement qui a été décrit est que la capacité 17 est rechargée avec des gaz renfermant du carburant, si bien que le rende­ment du moteur subit une légère diminution par rapport à un fonctionnement utilisant une source d'air compri­mé dont le rechargement n'est pas effectué à partir du cylindre du moteur.The disadvantage of the operating mode which has been described is that the capacity 17 is recharged with gases containing fuel, so that the efficiency of the engine undergoes a slight decrease compared to an operation using a source of compressed air whose reloading is not performed from the engine cylinder.

Il est possible de prévoir une came 21 d'une forme telle que la soupape s'ouvre en deux fois à cha­cun des tours effectués par le vilebrequin.It is possible to provide a cam 21 of a shape such that the valve opens twice in each of the turns performed by the crankshaft.

La came 21 est telle que la soupape 20 s'ou­vre dans un premier temps peu après que le cylindre ait atteint son point mort bas, si bien qu'une injec­tion pneumatique est réalisée comme décrit précédem­ment grâce au gaz sous pression contenu dans la capa­cité 17. La came 21 de forme complexe permet également une seconde ouverture de la soupape 20 pendant la pha­se de détente ou même pendant la phase d'échappement des gaz brûlés remplissant le cylindre 1, à un moment où la pression dans le cylindre est supérieure à la pression dans la capacité 17. La capacité 17 est donc rechargée par des gaz qui sont en grande partie des gaz brûlés ou des gaz renfermant une faible quantité résiduelle de carburant non brûlé.The cam 21 is such that the valve 20 first opens shortly after the cylinder has reached its bottom dead center, so that a pneumatic injection is carried out as described above thanks to the pressurized gas contained in the capacity 17. The cam 21 of complex shape also allows a second opening of the valve 20 during the expansion phase or even during the exhaust phase of the burnt gases filling the cylinder 1, at a time when the pressure in the cylinder is greater than the pressure in the capacity 17. The capacity 17 is therefore recharged by gases which are largely burnt gases or gases containing a small residual amount of unburned fuel.

La came 21 permet à la soupape 20 de se re­fermer une première fois, après l'injection, au début de la compression dans le cylindre, avant que la pression de l'air carburé ne soit suffisante pour que cet air pénètre dans la capacité 17. La soupape 20 reste ensuite fermée pendant toute la compression, la combustion et le début de la détente. Comme indiqué plus haut, la soupape 20 s'ouvre ensuite au cours de la détente ou au début de l'échappement, pendant un temps et avec une levée plus faible que lors de la première ouverture. En effet, la différence de pres­sion entre la chambre du cylindre 1 et la capacité 17 est alors bien plus élevée que lors de la première ouverture assurant l'injection du mélange carburant. La capacité 17 est donc mise en pression très rapide­ment par les gaz contenus dans la chambre du cylindre 1.The cam 21 allows the valve 20 to close a first time, after injection, at the start of compression in the cylinder, before the pressure of the carburetted air is sufficient for this air to enter the capacity 17 The valve 20 then remains closed during all of the compression, combustion and the start of expansion. As indicated above, the valve 20 then opens during expansion or at the start of the exhaust, for a time and with a lower lift than when the first opening. Indeed, the pressure difference between the chamber of the cylinder 1 and the capacity 17 is then much higher than during the first opening ensuring the injection of the fuel mixture. The capacity 17 is therefore put under pressure very quickly by the gases contained in the chamber of the cylinder 1.

Selon un mode particulier du dispositif représenté à la figure 1, il est possible de réaliser par l'injecteur 16 une injection discontinue de telle sorte que celui-ci n'injecte pas de carburant lorsque le remplissage de la capacité est en cours.According to a particular embodiment of the device represented in FIG. 1, it is possible to carry out by the injector 16 a discontinuous injection so that the latter does not inject fuel when the filling of the capacity is in progress.

Ceci permet un meilleur contrôle des régimes transitoires du moteur, en diminuant la concentration en carburant retenu dans la capacité.This allows better control of the transient engine speeds, by reducing the concentration of fuel retained in the capacity.

Une manière simple d'obtenir un tel fonction­nement est de ne faire fonctionner l'injecteur 16 que lorsque la soupape 20 est fermée.A simple way to obtain such operation is to operate the injector 16 only when the valve 20 is closed.

Sur les figures 2 et 3, on a représenté la partie supérieure d'un cylindre 30 d'un moteur à deux temps tel que décrit précédemment comportant un dis­positif d'injection 31 dans sa partie supérieure réa­lisé sous une forme différente de celle du dispositif 14 représenté sur la figure 1.Figures 2 and 3, there is shown the upper part of a cylinder 30 of a two-stroke engine as described above comprising an injection device 31 in its upper part produced in a form different from that of the device 14 shown in Figure 1.

L'injecteur pneumatique 32 débouchant dans la partie supérieure du cylindre 30 comporte comme précédemment une soupape 33 commandée par une came 34, un moyen d'alimentation en carburant liquide non re­présenté et un dispositif 35 fournissant à l'injecteur pneumatique 32 un gaz sous pression permettant la pul­vérisation et l'injection du carburant liquide.The pneumatic injector 32 opening into the upper part of the cylinder 30 comprises, as previously, a valve 33 controlled by a cam 34, a means for supplying liquid fuel not shown and a device 35 supplying the pneumatic injector 32 with gas under pressure allowing spraying and injection of liquid fuel.

Le dispositif 35 comporte un conduit 36 com­muniquant, à l'une de ses extrémités, avec la chambre du cylindre 30 par une lumière 37 disposée au-dessus des lumières d'échappement et de transfert du cylindre non représentées et à son autre extrémité, avec la chambre de l'injecteur pneumatique 32 à la partie su­périeure du cylindre. Un clapet 38 est disposé sur la conduite 36 et délimite sur cette conduite une partie amont communiquant avec le cylindre 30 et une partie aval communiquant avec l'injecteur 32. Le clapet 38 s'ouvre lorsque la pression différentielle entre l'amont et l'aval dans le conduit 36 dépasse une cer­taine valeur correspondant à la tare du clapet 38.The device 35 comprises a conduit 36 communicating, at one of its ends, with the cylinder chamber 30 by a light 37 arranged above the exhaust and transfer ports of the cylinder not shown and at its other end, with the pneumatic injector chamber 32 at the top of the cylinder. A valve 38 is disposed on the pipe 36 and delimits on this pipe an upstream part communicating with the cylinder 30 and a downstream part communicating with the injector 32. The valve 38 opens when the differential pressure between the upstream and the downstream in the conduit 36 exceeds a certain value corresponding to the tare weight of the valve 38.

La partie aval du conduit 36 est susceptible de constituer par elle-même une capacité de gaz sous pression en communication avec la chambre du clapet 32. Cette partie aval du conduit 36 peut également être mise en communication avec une capacité permet­tant le stockage de gaz sous pression.The downstream part of the duct 36 is capable of constituting by itself a capacity of pressurized gas in communication with the valve chamber 32. This downstream part of the duct 36 can also be put in communication with a capacity allowing the storage of gas under pressure.

On va maintenant se reporter à l'ensemble des figures 2, 3 et 4 pour décrire le fonctionnement du dispositif d'injection suivant le second mode de réalisation.We will now refer to all of Figures 2, 3 and 4 to describe the operation of the injection device according to the second embodiment.

Sur la figure 2, le piston 30a se déplace vers le haut à l'intérieur du cylindre 30 et réalise la compression d'un mélange carburé se trouvant dans la partie supérieure du cylindre. Le piston 30a masque la lumière 37 et le clapet 38 qui est soumis à des pressions amont et aval peu différentes reste fermé.In FIG. 2, the piston 30a moves upwards inside the cylinder 30 and carries out the compression of a fuel mixture located in the upper part of the cylinder. The piston 30a masks the light 37 and the valve 38 which is subjected to slightly different upstream and downstream pressures remain closed.

Sur la figure 4, on a représenté sous la forme d'une surface hâchurée le cycle de fonctionne­ment du moteur dans un diagramme pression des gaz contenus dans le cylindre en fonction du volume occupé par ces gaz. Le point de fonctionnement du moteur dé­crit la courbe 40 délimitant le cycle à sa partie in­férieure lorsque le piston se déplace vers le haut et la courbe limite supérieure 41 du cycle lorsque le piston 30a se déplace vers le bas.In FIG. 4, the operating cycle of the engine is represented in the form of a hatched surface in a pressure diagram of the gases contained in the cylinder as a function of the volume occupied by these gases. The engine operating point describes the curve 40 delimiting the cycle at its lower part when the piston moves up and the upper limit curve 41 of the cycle when the piston 30a moves down.

A la fin de la compression, le piston 30a atteignant son point mort haut, le volume V est mini­mum. L'allumage suive de la combustion se produit pendant la compression. La pression dans le cylindre atteint peu après son maximum et le piston se déplace vers le bas.At the end of compression, the piston 30a reaching its top dead center, the volume V is minimum. The ignition following combustion occurs during compression. The pressure in the cylinder reaches soon after its maximum and the piston moves down.

Lorsque la partie supérieure du piston 30a parvient au niveau de la lumière 37 (figure 3) le volume des gaz dans le cylindre a une valeur V0 et la pression de ces gaz, une valeur P2. Le point de fonc­tionnement du moteur correspond au point A de la figu­re 4. Le clapet 38 se soulève et les gaz contenus dans la chambre du cylindre 30 viennent remplir l'ensemble du conduit 35 comportant éventuellement une capacité de stockage de gaz sous pression en aval du clapet 38.When the upper part of the piston 30a reaches the level of the light 37 (FIG. 3) the volume of the gases in the cylinder has a value V0 and the pressure of these gases, a value P2. The engine operating point corresponds to point A in FIG. 4. The valve 38 lifts and the gases contained in the cylinder chamber 30 fill the entire duct 35 possibly including a storage capacity for pressurized gas downstream valve 38.

En effet, ainsi qu'il sera montré plus loin, la partie aval du conduit 35 est, lors de l'ouverture des lumières 37, à une pression inférieure à P2.Indeed, as will be shown later, the downstream part of the conduit 35 is, when the apertures 37 are opened, at a pressure below P2.

Le piston 30a continue à se déplacer vers le bas et découvre les lumières d'échappement. La pres­sion diminue dans la chambre du cylindre pendant les phases d'échappement et de balayage par l'air frais. Le clapet 38 se referme très rapidement dès que la pression est inférieure à P2. La fermeture du clapet 38 assure donc la constitution d'une réserve de gaz à une pression sensiblement égale à P2.The piston 30a continues to move downwards and discovers the exhaust ports. The pressure decreases in the cylinder chamber during the exhaust and sweeping phases with fresh air. The valve 38 closes very quickly as soon as the pressure is less than P2. Closing the valve 38 therefore ensures the constitution of a gas reserve at a pressure substantially equal to P2.

Après son passage au point mort bas, le pis­ton 30a remonte dans le cylindre; le point de fonc­tionnement sur la figure 4 décrit la courbe 40.After passing to bottom dead center, the piston 30a rises in the cylinder; the operating point in FIG. 4 describes the curve 40.

Avant le début de la compression, la came 34 commande l'ouverture de la soupape 33 de l'injecteur 32 (point de fonctionnement I). Du carburant liquide est pulvérisé et injecté dans la partie supérieure du cylindre 30 par le gaz à pression P2 retenu dans le conduit 35 et/ou la capacité de stockage, en aval du clapet 38. L'injecteur pneumatique peut être conçu pour se refermer assez rapidement, ceci étant détermi­né lors de la conception ou de la mise au point du mo­teur par la loi de la came 34, la pression en aval du clapet 38 s'établit à une valeur inférieure à P2.Before the start of compression, the cam 34 controls the opening of the valve 33 of the injector 32 (operating point I). Liquid fuel is sprayed and injected into the upper part of the cylinder 30 by the pressure gas P2 retained in the duct 35 and / or the storage capacity, downstream of the valve 38. The pneumatic injector can be designed to close sufficiently quickly, this being determined during the design or the development of the engine by the law of the cam 34, the pressure downstream of the valve 38 is established at a value less than P2.

Le mélange carburé contenu dans le cylindre est alors comprimé par le piston 30a. La partie supé­rieure du piston 30a vient masquer l'ouverture 37 au début de la compression (point B sur la figure 4). Le volume résiduel dans le cylindre est V0 et la pression des gaz P1. La pression P1, comme il est visible sur le diagramme de la figure 4, est notablement inférieu­re à la pression P2. Le pression dans le conduit 35 en amont du clapet 38 s'établit donc à la valeur P1 < P2. Cette position du piston 30a est représentée sur la figure 2.The fuel mixture contained in the cylinder is then compressed by the piston 30a. The upper part of the piston 30a masks the opening 37 at the start of the compression (point B in FIG. 4). The residual volume in the cylinder is V0 and the gas pressure P1. The pressure P1, as can be seen in the diagram in FIG. 4, is notably lower than the pressure P2. The pressure in the conduit 35 upstream of the valve 38 therefore becomes established at the value P1 <P2. This position of the piston 30a is shown in FIG. 2.

Les conditions de l'injection sont telles que la pression en aval du clapet 38 s'est établie à une valeur P3 comprise entre P2 et P1.The conditions of the injection are such that the pressure downstream of the valve 38 is established at a value P3 between P2 and P1.

Sinon, si le conduit 36 s'est suffisamment vidé pendant l'injection pour atteindre une pression inférieure à P1, alors dans ce cas, le clapet 38 s'ou­ vre pendant la compression pour permettre au conduit 36 d'atteindre une pression proche de P1 au moment où la montée du piston masque la lumière 37. La suite se déroule de façon identique dans les deux cas.Otherwise, if the pipe 36 has emptied enough during the injection to reach a pressure below P1, then in this case, the valve 38 opens or vre during compression to allow the conduit 36 to reach a pressure close to P1 at the time when the rise of the piston masks the light 37. The sequence takes place identically in both cases.

Ainsi, le clapet 38 reste donc fermé jus­qu'au moment où le point de fonctionnement revient en A (configuration de la figure 3). Le piston 30a décou­vre la lumière 37, si bien que la partie amont du conduit 35 est mise à la pression P2 > P3. Le clapet 38 s'ouvre et la partie aval du conduit 35 constituant la capacité de réserve de gaz d'injection se recharge en gaz brûlés à la pression P2.Thus, the valve 38 therefore remains closed until the point of operation returns to A (configuration of Figure 3). The piston 30a discovers the light 37, so that the upstream part of the conduit 35 is brought to pressure P2> P3. The valve 38 opens and the downstream part of the conduit 35 constituting the injection gas reserve capacity is recharged with burnt gases at pressure P2.

Sur la figure 5, on a représenté la partie supérieure de deux cylindres 40C et 41C d'un moteur à deux temps à plusieurs cylindres. Un dispositif d'in­jection pneumatique 42 est associé au cylindre 40C et comporte un injecteur pneumatique dont la chambre dé­bouche dans la partie supérieure du cylindre 40C au niveau d'un siège auquel est associée la soupape 43 de l'injecteur. Le dispositif d'injection 42 comporte également un moyen d'alimentation de l'injecteur pneu­matique en carburant liquide non représenté et un conduit 45 joignant la partie supérieure de la chambre du cylindre 41C à la chambre de l'injecteur pneumati­que 42 du cylindre 40C.In Figure 5, there is shown the upper part of two cylinders 40C and 41C of a two-stroke engine with several cylinders. A pneumatic injection device 42 is associated with the cylinder 40C and comprises a pneumatic injector, the chamber of which opens into the upper part of the cylinder 40C at the level of a seat with which the valve 43 of the injector is associated. The injection device 42 also comprises a means for supplying the pneumatic injector with liquid fuel, not shown, and a conduit 45 joining the upper part of the chamber of the cylinder 41C to the chamber of the pneumatic injector 42 of the cylinder 40C.

Les deux cylindres 40C et 41C sont choisis de façon à présenter un décalage dans leur cycle de fonctionnement tel qu'à la fin du balayage et avant la compression dans le cylindre 40C, au moment où l'in­jection pneumatique de carburant va être commandée par ouverture de la soupape 43, le piston 41a du cylindre 41 en phase de détente découvre la lumière 44 faisant communiquer le conduit 45 avec la chambre de combus­tion du cylindre 41C. Les gaz dans le cylindre 41C sont alors à une pression très supérieure à la pres­sion des gaz dans le cylindre 40C, si bien qu'à l'ou­verture de la soupape 43 la pulvérisation et l'injec­tion du carburant dans le cylindre 40C sont assurées par les gaz sous pression de la chambre du cylindre 41C.The two cylinders 40C and 41C are chosen so as to present an offset in their operating cycle such that at the end of the sweep and before the compression in the cylinder 40C, at the moment when the pneumatic injection of fuel will be controlled by opening of the valve 43, the piston 41a of the cylinder 41 in the expansion phase discovers the light 44 making the conduit 45 communicate with the combustion chamber of the cylinder 41C. The gases in cylinder 41C are then at a pressure much higher than the pressure of the gases in the cylinder 40C, so that at the opening of the valve 43 the spraying and the injection of the fuel into the cylinder 40C are ensured by the pressurized gases of the 41C cylinder chamber.

On a représenté sur la figure 5 la configu­ration des cylindres 40C et 41C, juste avant l'injec­tion de carburant dans le cylindre 40C, au moment où la lumière 44 du cylindre 41C est démasquée par le piston 41a se déplaçant vers le bas.FIG. 5 shows the configuration of the cylinders 40C and 41C, just before the injection of fuel into the cylinder 40C, when the lumen 44 of the cylinder 41C is unmasked by the piston 41a moving downwards.

Le cylindre 41C comporte un dispositif d'in­jection de carburant 46 analogue au dispositif 42 du cylindre 40C, dont le conduit 47 d'admission de gaz sous pression est relié à un cylindre du moteur pré­sentant un décalage dans son cycle de fonctionnement par rapport au cylindre 41C analogue au décalage exis­tant entre les cylindres 40C et 41C.The cylinder 41C includes a fuel injection device 46 similar to the device 42 of the cylinder 40C, the conduit 47 for admission of pressurized gas being connected to an engine cylinder having an offset in its operating cycle relative to the cylinder 41C analogous to the offset existing between the cylinders 40C and 41C.

Sur la figure 6, on a représenté une varian­te de réalisation du dispositif d'injection 32 repré­senté sur les figures 2 et 3. Les éléments correspon­dants sur les figures 2 et 3 d'une part et 6 d'autre part portent les mêmes repères avec l'exposant ′ en ce qui concerne les éléments du dispositif représenté sur la figure 6.In Figure 6, there is shown an alternative embodiment of the injection device 32 shown in Figures 2 and 3. The corresponding elements in Figures 2 and 3 on the one hand and 6 on the other hand have the same references with the exponent ′ as regards the elements of the device shown in FIG. 6.

Le dispositif d'injection 32′ comporte un conduit 36′ analogue au conduit 36 du dispositif re­présenté sur les figures 2 et 3 communiquant, à l'une de ses extrémités par une lumière 37′, avec la chambre intérieure du cylindre 30′ et, à son autre extrémité, avec la chambre de l'injecteur communiquant par l'in­termédiaire de la soupape 33′, avec la partie supé­rieure du cylindre 30′. Un clapet 38′ est intercalé sur le conduit 36′ et sépare ce conduit 36′ en une partie amont communiquant avec la lumière 37′ du cy­lindre 30′ et une partie aval communiquant avec l'in­jecteur pneumatique.The injection device 32 ′ comprises a conduit 36 ′ similar to the conduit 36 of the device shown in FIGS. 2 and 3 communicating, at one of its ends by a light 37 ′, with the interior chamber of the cylinder 30 ′ and at its other end, with the injector chamber communicating via the valve 33 ′, with the upper part of the cylinder 30 ′. A valve 38 ′ is interposed on the conduit 36 ′ and separates this conduit 36 ′ into a upstream part communicating with the light 37 ′ of the cylinder 30 ′ and a downstream part communicating with the pneumatic injector.

En amont du clapet 38′, le conduit 36′ est relié par l'intermédiaire d'un conduit 50 et d'un cla­pet 51 avec une source d'air frais qui peut être cons­tituée par l'air atmosphérique, le clapet 51 ayant son entrée à l'air libre.Upstream of the valve 38 ′, the conduit 36 ′ is connected by means of a conduit 50 and a valve 51 with a source of fresh air which can be constituted by atmospheric air, the valve 51 having its entry into the open air.

Pendant la phase d'échappement des gaz et de balayage du cylindre 30′ du moteur deux temps, la chambre de ce cylindre 30′ peut être mise en dépres­sion par les effets d'onde d'échappement. Cette mise en dépression provoque l'ouverture du clapet 51 et le balayage de la partie amont du conduit 36′ dans le cy­lindre 30 par de l'air frais.During the exhaust gas and sweeping phase of the cylinder 30 ′ of the two-stroke engine, the chamber of this cylinder 30 ′ can be depressed by the effects of the exhaust wave. This vacuum causes the valve 51 to open and the upstream portion of the duct 36 ′ to sweep through the cylinder 30 with fresh air.

Le procédé et le dispositif suivant l'inven­tion présentent dans tous les cas l'avantage d'utili­ser pour la pulvérisation et l'injection du carburant, du gaz sous pression disponible dans le moteur même. Ce gaz sous pression peut d'autre part être prélevé à proximité de l'endroit où il est utilisé pour l'injec­tion de carburant dans le cylindre. Les pressions de gaz peuvent d'autre part être très élevées par rapport à la pression dans le cylindre au moment de l'injec­tion, ce qui améliore d'autant la qualité de la pulvé­risation et de l'injection de carburant. Il est d'autre part possible de limiter à une valeur faible la perte de rendement du moteur en utilisant principa­lement des gaz brûlés pour assurer l'injection.The method and the device according to the invention have in all cases the advantage of using, for spraying and injecting fuel, pressurized gas available in the engine itself. This pressurized gas can also be taken near the place where it is used for injecting fuel into the cylinder. Gas pressures can also be very high compared to the pressure in the cylinder at the time of injection, which improves the quality of the fuel spraying and injection. On the other hand, it is possible to limit the loss of engine efficiency to a low value by using mainly burnt gases for injection.

L"invention ne se limite pas aux modes de réalisation qui ont été décrits.The invention is not limited to the embodiments which have been described.

On peut en particulier envisager l'utilisa­tion d'injecteurs de formes différentes, de capacités de stockage des gaz sous pression dans des disposi­ tions variées par rapport à l'injecteur et aux cylin­dres et des cames de commande de l'injecteur de formes diverses.In particular, it is possible to envisage the use of injectors of different shapes, of capacities for storing pressurized gases in disposi various tions with respect to the injector and to the cylinders and control cams of the injector of various shapes.

L'invention s'applique non seulement aux mo­teurs à deux temps mais encore à tout moteur altena­tif à combustion interne dans lequel sont réalisés in­dépendamment une introduction et un balayage d'air frais et une injection pneumatique de carburant.The invention applies not only to two-stroke engines but also to any internal combustion internal engine in which an introduction and a sweep of fresh air and a pneumatic fuel injection are carried out independently.

On ne sortira pas du cadre de la présente invention en utilisant à la place de la soupape 20, 33, 43, 46 ou 33′ une soupape automatique fonctionnant comme un clapet, un boisseau tournant ou une soupape à commande électromagnétique.It will not depart from the scope of the present invention to use in place of the valve 20, 33, 43, 46 or 33 ′ an automatic valve operating as a valve, a rotating plug or an electromagnetically controlled valve.

Claims (14)

1. - Procédé d'injection pneumatique de car­burant dans un cylindre d'un moteur alternatif à com­bustion interne comportant au moins un cylindre (1, 30, 30′, 40) dans lequel on réalise indépendamment un balayage par de l'air frais non carburé et une injec­tion de carburant liquide pulvérisé par un gaz sous pression, à des instants déterminés du cycle de fonc­tionnement du moteur, caractérisé par le fait que la pulvérisation et l'injection du carburant dans le cy­lindre (1, 30, 30′, 40C) sont réalisées par des gaz prélevés dans un cylindre du moteur.1. - A method of pneumatically injecting fuel into a cylinder of a reciprocating internal combustion engine comprising at least one cylinder (1, 30, 30 ′, 40) in which a sweep is carried out independently of fresh air not carburetor and an injection of liquid fuel sprayed by a pressurized gas, at determined times in the engine operating cycle, characterized in that the spraying and injection of fuel into the cylinder (1, 30, 30 ′, 40C ) are produced by gases taken from an engine cylinder. 2. - Procédé d'injection suivant la revendi­cation 1, caractérisé par le fait que les gaz sont prélevés dans le cylindre (1, 30, 30′, 40C) dans le­quel a lieu l'injection pneumatique.2. - Injection method according to claim 1, characterized in that the gases are taken from the cylinder (1, 30, 30 ′, 40C) in which the pneumatic injection takes place. 3. - Procédé d'injection suivant la revendi­cation 2, caractérisé par le fait que les gaz sont prélevés dans le cylindre (1) par l'ouverture (18) du cylindre (1) dans laquelle on effectue l'injection de carburant.3. - Injection method according to claim 2, characterized in that the gases are taken from the cylinder (1) through the opening (18) of the cylinder (1) in which the fuel injection is carried out. 4. - Procédé d'injection suivant la revendi­cation 2, caractérisé par le fait que les gaz sont prélevés par une lumière (37) dans la partie de la surface interne du cylindre (30) balayée par le piston (30a).4. - An injection method according to claim 2, characterized in that the gases are taken by a light (37) in the part of the internal surface of the cylinder (30) swept by the piston (30a). 5. - Procédé d'injection suivant la revendi­cation 1, caractérisé par le fait que les gaz sont prélevés dans un cylindre (41C) différent du cylindre (40C) dans lequel on réalise une injection de carbu­rant, à l'aide de ces gaz prélevés.5. - injection method according to claim 1, characterized in that the gases are sampled in a cylinder (41C) different from the cylinder (40C) in which a fuel injection is carried out, using these sampled gases . 6. - Dispositif d'injection pneumatique de carburant dans un cylindre (1, 30, 30′ 40C) d'un mo­teur alternatif à combustion interne comportant au moins un cylindre (1, 30, 30′, 40C), un moyen d'ali­mentation du cylindre en air non carburé de balayage et un dispositif d'injection pneumatique de carburant (14, 32, 32′, 42) comportant un injecteur pneumatique ayant une chambre débouchant dans le cylindre, un moyen d'alimentation de l'injecteur pneumatique en carburant liquide et un moyen d'alimentation de l'in­jecteur pneumatique en gaz sous pression pour la pul­vérisation et l'injection du carburant sous forme di­visée dans le cylindre (1, 30, 30′, 40C), caractérisé par le fait que le moyen d'alimentation (17, 35, 35′) de l'injecteur en gaz sous pression est relié à la chambre d'un cylindre du moteur pour son alimentation par les gaz contenus dans le cylindre.6. - Pneumatic fuel injection device in a cylinder (1, 30, 30 ′ 40C) of an alternative internal combustion engine comprising at at least one cylinder (1, 30, 30 ′, 40C), a means for supplying the non-carburetted sweep air to the cylinder and a pneumatic fuel injection device (14, 32, 32 ′, 42) comprising a pneumatic injector having a chamber opening into the cylinder, means for supplying the pneumatic injector with liquid fuel and means for supplying the pneumatic injector with pressurized gas for spraying and injecting the fuel in divided form in the cylinder (1, 30, 30 ′, 40C), characterized in that the supply means (17, 35, 35 ′) of the pressurized gas injector is connected to the chamber of an engine cylinder for its supply by the gases contained in the cylinder. 7. - Dispositif d'injection suivant la reven­dication 6, caractérisé par le fait que le moyen d'a­limentation (17) de l'injecteur pneumatique en gaz sous pression est constitué par une capacité de sto­ckage reliée à la chambre du cylindre (1) dans lequel a lieu l'injection pneumatique, par l'intermédiaire de la chambre de l'injecteur pneumatique débouchant dans la partie supérieure du cylindre (1) au niveau d'un siège (18) d'une soupape de fermeture et d'ouverture (20).7. - Injection device according to claim 6, characterized in that the supply means (17) of the pneumatic injector in pressurized gas is constituted by a storage capacity connected to the cylinder chamber (1) in which the pneumatic injection takes place, by means of the pneumatic injector chamber opening into the upper part of the cylinder (1) at the level of a seat (18) of a closing and opening valve (20). 8. - Dispositif d'injection suivant la reven­dication 7, caractérisé par le fait que la soupape (20) est commandée pour son ouverture par une came (21) d'une forme et d'une disposition réalisant l'ou­verture de la soupape une fois par cycle, pendant l'injection précédant la compression ou à son début et pendant une partie au moins de la phase de compres­sion.8. - Injection device according to claim 7, characterized in that the valve (20) is controlled for its opening by a cam (21) of a shape and an arrangement providing the opening of the valve a times per cycle, during the injection preceding compression or at its start and during at least part of the compression phase. 9. - Dispositif d'injection suivant la reven­dication 7, caractérisé par le fait que la soupape (20) est commandée par une came (21) d'une forme et d'une disposition assurant l'ouverture de la soupape deux fois par cycle, une première fois avant la com­ pression, pour réaliser l'injection de carburant et une seconde fois, pendant la détente, pour réaliser le rechargement de la capacité (17) en gaz sous pression.9. - injection device according to claim 7, characterized in that the valve (20) is controlled by a cam (21) of a shape and a provision ensuring the opening of the valve twice per cycle , a first time before the com pressure, to carry out the fuel injection and a second time, during expansion, to carry out the recharging of the capacity (17) in pressurized gas. 10. - Dispositif d'injection suivant la re­vendication 6, caractérisé par le fait que le dispo­sitif (35, 35′) d'alimentation de l'injecteur (32) en gaz sous pression est constitué par un conduit commu­niquant à l'une de ses extrémités avec la chambre du cylindre (30, 30′) par une lumière (37) disposée sur la surface interne de la chambre du cylindre (30) ba­layée par le piston (30a) et à son autre extrémité avec la chambre de l'injecteur pneumatique (32) débou­chant dans la chambre du cylindre (30, 30′) au niveau d'un siège de soupape (33, 33′), un clapet (38, 38′) étant disposé sur le conduit (36, 36′) et délimitant une partie amont de ce conduit en communication avec la chambre du cylindre (37, 37′) par l'intermédiaire de la lumière (36, 36′) et une partie aval en communi­cation avec la chambre de l'injecteur (32), le clapet (38, 38′) pouvant être déplacé par pression différen­tielle dans le sens allant de l'amont vers l'aval.10. - injection device according to claim 6, characterized in that the device (35, 35 ′) for supplying the injector (32) with pressurized gas is constituted by a conduit communicating with one of its ends with the cylinder chamber (30, 30 ′) by a light (37) disposed on the internal surface of the cylinder chamber (30) swept by the piston (30a) and at its other end with the chamber of the pneumatic injector (32) opening into the cylinder chamber (30, 30 ′) at a valve seat (33, 33 ′), a valve (38, 38 ′) being arranged on the duct (36, 36 ′ ) and delimiting an upstream part of this conduit in communication with the cylinder chamber (37, 37 ′) via the light (36, 36 ′) and a downstream part in communication with the injector chamber (32 ), the valve (38, 38 ′) being able to be moved by differential pressure in the direction from upstream to downstream. 11. - Dispositif suivant la revendication 10, caractérisé par le fait que la partie amont du conduit (35, 35′) est reliée par l'intermédiaire d'un conduit (50) et d'un clapet (51) à une source de gaz de bala­yage du conduit amont (36′).11. - Device according to claim 10, characterized in that the upstream part of the conduit (35, 35 ′) is connected via a conduit (50) and a valve (51) to a source of purge gas from the upstream duct (36 ′). 12. Dispositif suivant la revendication 6, dans le cas d'un moteur multicylindre caractérisé par le fait que le dispositif d'alimentation en gaz sous pression de l'injecteur pneumatique (42) communiquant avec la chambre d'un premier cylindre (40C) est cons­titué par un conduit (45) communiquant à l'une de ses extrémités avec la chambre d'un second cylindre (41C), par une lumière (44) disposée sur la surface interne du second cylindre (41C) balayée par le piston cor­respondant (41a) et à son autre extrémité, avec la chambre de l'injecteur pneumatique de carburant (42) communiquant avec la chambre du premier cylindre (40C).12. Device according to claim 6, in the case of a multi-cylinder engine characterized in that the device for supplying pressurized gas to the pneumatic injector (42) communicating with the chamber of a first cylinder (40C) consists of a conduit (45) communicating at one of its ends with the chamber of a second cylinder (41C), by a lumen (44) disposed on the internal surface of the second cylinder (41C) swept by the corresponding piston (41a) and at its other end, with the chamber of the pneumatic fuel injector (42) communicating with the chamber of the first cylinder (40C). 13. Dispositif selon l'une des revendications 6 à 12, caractérisé en ce que l'injecteur pneumatique comporte un injecteur de carburant à fonctionnement dis­continu.13. Device according to one of claims 6 to 12, characterized in that the pneumatic injector comprises a fuel injector with discontinuous operation. 14. Dispositif selon la revendication 13, caractérisé en ce que ledit injecteur de carburant ne fonctionne que lorsque ladite soupape est fermée.14. Device according to claim 13, characterized in that said fuel injector operates only when said valve is closed.
EP88403381A 1987-12-30 1988-12-30 Device for pneumatically injecting fuel Expired - Lifetime EP0323368B1 (en)

Applications Claiming Priority (2)

Application Number Priority Date Filing Date Title
FR8718359 1987-12-30
FR8718359A FR2625532B1 (en) 1987-12-30 1987-12-30 METHOD FOR PNEUMATIC FUEL INJECTION IN A CYLINDER OF AN INTERNAL COMBUSTION ENGINE AND CORRESPONDING INJECTION DEVICE

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EP0323368A1 true EP0323368A1 (en) 1989-07-05
EP0323368B1 EP0323368B1 (en) 1994-06-22

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EP (1) EP0323368B1 (en)
JP (1) JP2777893B2 (en)
DE (1) DE3850378T2 (en)
FR (1) FR2625532B1 (en)
IN (1) IN172186B (en)

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EP0458670A1 (en) * 1990-05-21 1991-11-27 Institut Français du Pétrole Method of pneumatic fuel injection in a two-stroke engine and such a two-stroke engine

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Also Published As

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US5027765A (en) 1991-07-02
DE3850378D1 (en) 1994-07-28
DE3850378T2 (en) 1994-11-17
JPH02223669A (en) 1990-09-06
JP2777893B2 (en) 1998-07-23
FR2625532B1 (en) 1993-04-23
FR2625532A1 (en) 1989-07-07
IN172186B (en) 1993-05-01
EP0323368B1 (en) 1994-06-22

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