EP3568579A1

EP3568579A1 - Valve-controlled ignition prechamber

Info

Publication number: EP3568579A1
Application number: EP18713713.8A
Authority: EP
Inventors: Vianney Rabhi
Original assignee: Individual
Current assignee: Individual
Priority date: 2017-01-12
Filing date: 2018-01-08
Publication date: 2019-11-20
Also published as: CN110291278B; AU2018207981B2; WO2018130772A1; KR20190104551A; AU2018207981A1; CA3048883A1; JP7214638B2; CN110291278A; FR3061743B1; FR3061743A1; KR102581717B1; JP2020505542A

Abstract

The valve-controlled ignition pre-chamber (1) is intended for an internal combustion engine (2) which has a combustion chamber (5) in which a main charge (30) more less diluted with a neutral gas is ignited, said prechamber (1) comprising a stratification cavity (6) into which ignition means (11) open and into which a stratification injector (8) can inject a pressurized readily-inflammable pilot charge (9), a stratification valve (13) being able to close off the stratification duct (7) in full or in part, notably under the effect of the pressure of the gases obtaining in the combustion chamber (11).

Description

PRE-CLAMP CHAMBER

The present invention relates to a valve ignition prechamber which makes it possible to ignite a main charge introduced into the combustion chamber of an internal combustion engine by means of a pilot charge ignited by a spark, said antechamber being designed to optimize the efficiency of said pilot charge to ignite said main charge.

The maximum and average efficiency of reciprocating internal combustion engines according to the state of the art is relatively low. In automobiles, the maximum efficiency is of the order of thirty-five percent for Otto-cycle spark ignition engines, and of the order of forty percent for Diesel cycle engines. With regard to the average efficiency in current use of automobile engines, it is most often less than twenty percent for spark ignition engines, and twenty-five percent for diesel engines.

In said engines, the fraction of the energy released by the combustion of the fuel and which is not transformed into useful work is mainly dissipated in the form of heat in the cooling system and the exhaust of said engines.

In addition to poor performance, alternative internal combustion engines used in automobiles produce polluting gases and particles that are harmful to the environment and to health. Despite these unattractive features, for lack of other solutions offering a better energy, environmental, functional, and economical compromise, Otto or Diesel internal combustion engines heat up almost all the motor vehicles in circulation in the world. . This situation explains the significant research and development efforts made by the engine manufacturers to improve by all means the energy and environmental balance of internal combustion engines. These efforts are aimed in particular at perfecting the technologies that constitute said engines, and adding to these new features that allow the implementation of new strategies.

Among these strategies is the dilution of the air and fuel load of the reciprocating internal combustion engines with either a neutral gas or fresh air rich in oxygen. It is to this dilution that the present invention is addressed which is particularly intended for internal combustion engines with spark-ignition internal combustion that most often consume either gasoline or natural gas.

Diluting the charge of spark-ignition engines with fresh air or with previously cooled exhaust gases makes it possible to increase the average and / or maximum thermodynamic efficiency of said engines. The result is reduced fuel consumption at the same job. When spark ignition engines operate in partial torque, introducing a dilute load into their cylinder (s) produces less pumped losses than introducing an undiluted charge. The reduction of said losses results from the fact that the diluted load is larger with the same energy content. Thus, to introduce the same amount of energy in said cylinder (s), the throttling at the intake of said engines usually performed by means of a throttle is less pronounced, and the pressure of the gases that occur at said admission is higher. In addition, the same energy introduced into the cylinder (s) of spark ignition engines, dilute the load increases the mass and the total heat capacity of the latter. Thus, all things being equal, the combustion of said charge takes place at a lower temperature. In addition to reducing the amount of nitrogen oxides produced by the combustion, said low temperature reduces heat losses to the walls of the cylinder (s) resulting from the transfer by said load of a portion of its heat to said walls.

Finally, particularly if the feedstock is diluted with a neutral gas that is low in oxygen or even free of oxygen, the said feedstock is less sensitive to the uncontrolled self-ignition of the air-fuel mixture. This self-ignition is responsible for rattling, an undesirable phenomenon characterized by a detonating combustion that deteriorates the efficiency of spark ignition engines and damages the mechanical components that constitute them. The desensitization to rattling that provides the dilution of the load allows said engines to either operate at higher compression ratio, or to operate with ignition that is triggered at the most favorable time possible performance, or both.

In this particular context of diluted air and fuel charges, there are spark ignition engines operating stoichiometry of said engines operating in excess air also called "lean".

The engines operating with stoichiometry are only compatible with a three-way catalyst, a device known per se that post-processes the pollutants resulting from combustion. Said catalyst is responsible for burning hydrocarbons that have not been burned in the combustion chamber of the engine. The products of this combustion are water vapor and carbon dioxide already present in the atmosphere. Said three-way catalyst also finalizes the oxidation of notoriously polluting carbon monoxide to also convert it to carbon dioxide, and reduces the nitrogen oxides to convert them into atmospheric dinitrogen which constitutes about seventy-eight percent of the carbon dioxide. terrestrial atmosphere, and which is by nature non-polluting.

The reduction of nitrogen oxides by three-way catalysis requires that the charge introduced into the engine be stoichiometric, that is to say that it contains the right amount of oxygen necessary for the combustion of hydrocarbons contained in said charge. An excess of oxygen makes it impossible to reduce the oxides of nitrogen by the three-way catalyst. It is therefore not possible to post-treat the nitrogen oxides contained in the exhaust gases of the engines operating in excess of air by means of a three-way catalyst. This explains why - in response to ever more stringent environmental regulations - engines operating in excess of air now receive a device specifically designed to reduce nitrogen oxides such as a nitrogen oxide trap or a catalytic reduction device selective oxides of nitrogen to urea. This apparatus is generally placed at the outlet of a two-way oxidation catalyst which has previously burned unburnt hydrocarbons and which has completed the oxidation of carbon monoxide, and more and more often, of a particulate filter.

Diesel engines operating naturally in excess of air, since the entry into force of the Euro VI standard in Europe, almost all European diesel cars are equipped with a device that post-processes nitrogen oxides to transform them in dinitrogen.

The problem of these devices is that they are expensive, complex, and that their size and maintenance requirements are high to the point that said devices are almost used only on diesel engines that can in practice operate only in excess of 'air.

As far as spark ignition engines are concerned, engine manufacturers strive by all means to make them work with stoichiometry so that they remain compatible with a three-way catalytic converter which is simply and inexpensively.

To benefit from the reduction in fuel consumption induced by the dilution of the charge of spark-ignition engines without having to suffer the particular economic drawbacks of a nitrogen oxide trap or a selective catalytic reduction device for oxides from nitrogen to urea, it is therefore necessary to dilute said charge of said engines not with air rich in oxygen, but with a neutral gas devoid of oxygen.

This latter gas is usually provided by the recycling of the exhaust gas of the engine itself, said gases no longer containing oxygen and being available and abundant. This strategy is known under the name of "recirculation of exhaust gas" and more precisely under the acronym "EGR" for "Exhaust Gas Recirculation".

Said gas exiting at high temperature at the exhaust of the spark ignition engine, to prevent them from overheating the load introduced into said engine, it is necessary to reduce the temperature before mixing with the fresh gas. This strategy is known as the Anglo-Saxon "Cooled EGR", which specifies that the recirculated exhaust gas is cooled prior to mixing with the fresh gas admitted by said engine. The French engine manufacturers finally use the term "franglais" of "cooled EGR", easily understandable and easy to use. Prior cooling of the EGR gases is required for at least two purposes.

First, it is necessary that the temperature of the gas-EGR / gas-fresh mixture admitted by the spark ignition engine remains low so that the volumetric efficiency of said engine remains high when operating at full torque. Indeed, for a given intake pressure, the mass of said mixture introduced into the cylinder (s) of said engine is all the more important that said mixture is cold. Prior cooling of the EGR gas is made even more essential if said engine is supercharged by a turbocharger or by any other means.

Second, the hotter the gas-EGR / gas-fresh mixture, the more it favors the occurrence of rattling which is unfavorable to the performance of said engine.

The problem is that the diluted charge to the cooled EGR is low in oxygen. This is paradoxical since it is also the aim sought in particular for the charge to remain stoichiometric and resistant to rattling. This oxygen depletion results in a combustion initiation that is more difficult to obtain and a slower combustion development than when said charge is undiluted at the cooled EGR. In a spark ignition engine, the initialization of the combustion occurs by creating a high temperature electric arc between two electrodes distant from each other by a few tenths of a millimeter.

When the air-fuel charge is heavily diluted with cooled EGR, the electric arc passes through a globally poor mixture of oxygen and fuel. The risk of a misfire increases if, by accident, the space of a few tenths of a millimeter separating the cathode from the anode of the spark plug does not contain a gas-EGR / gas-charge mixture sufficiently burnable because indeed heterogeneities are inevitably created in the three-dimensional space of the combustion chamber, with pockets richer in oxygen and / or fuel than others.

If combustion is initiated as desired, the fuel energy in the charge begins to release as heat and the flame begins to expand. For this, by successive approaches, said flame communicates its heat to the surrounding gas-EGR / gas-fresh mixture, burnable layer after burnable layer. Each layer is brought to its ignition temperature by the previous layer, burns, and releases heat that it communicates to the next layer and so on. According to the principle of the chain reaction, the flame propagates in the three-dimensional space of the combustion chamber of the spark ignition engine.

The main problem of cooled EGR is that it makes the initialization of combustion difficult, and then considerably slows the development of the latter both because of the overall reduction of its temperature, and because of the heterogeneities of oxidant and / or fuel found in the volume of the combustion chamber and therefore, on the path of the flame. Moreover, it is found experimentally that the higher the cooled EGR charge content, the more unstable the engine becomes. From a certain content, misfires occur and the efficiency - which hitherto tended to increase with the cooled EGR content of the charge - decreases. Beyond a certain content of said EGR, the spark ignition engine stops, the combustion is unable to initialize.

Note also that the content of the exhaust gas in unburned hydrocarbons and carbon monoxide increases in parallel with the cooled EGR content of the load. This is due to both pockets of mixture too poor to burn properly encountered by the flame on its path, and the thickening of the boundary layer flame jam near the cold internal walls of the combustion chamber of the engine.

Still experimentally, it is also found that the higher the ignition power is, the more it is possible to increase the cooled EGR content of the load without greatly altering the stability of the engine.

As such, many research laboratories - such as the South West Research Institute in the United States - have developed increasingly powerful electric ignition devices to push back the accessible limits of cooled EGR content in the United States. load. The purpose of this strategy is of course to improve the efficiency of the spark ignition engine.

The problem of overbidding the power of electric ignitions is that their performance decreases rapidly with their power. Therefore, more electrical power is needed to get less and less additional ignition power.

In addition, high electrical power is of interest only if the electrodes of the candle are moved away from each other to give more chances to the spark to cross a burnable pocket, or while the The duration of the spark is increased, or the spark is repeated. This leads to increasingly higher voltages and electrical powers which make it more difficult to achieve the electrical insulation of the spark plug while drastically reducing the life of the spark plug. The difficulty in igniting the charge also stems from the fact that the cooled EGR is all the more interesting on supercharged spark ignition engines which are sought by all means to reduce the sensitivity to rattling. However, the higher the supercharging pressure, the greater the density of the gas-EGR / gas-fresh mixture is important between the electrodes of the spark plug at the moment of the spark, and more voltage is required to cause said spark. From this point of view, the cooled EGR does not go in the right direction because at the same energy introduced into the cylinder of the engine, the mass of gas which is between the electrodes increases as well as the resistance of said gas to the inflammation. It is noted that the patent No. FR 2 986 564 belonging to the applicant is a robust response to these problems. The spark ignition and high pressure lamination device for an internal combustion engine referred to in said patent proposes to inject under high pressure, in the center of the spark plug and shortly before the triggering of the spark, an approximately stoichiometric pilot charge, highly burnable because undiluted with cooled EGR, and potentially slightly rich in fuel.

Once injected by said device, said pilot charge bathing the electrodes of the candle, as soon as an electric arc is formed between said electrodes, said charge ignites immediately and releases the energy it contains. Thus, said load itself is the ignition means in itself whose power is several hundred to several thousand times greater than that of the electric arc that allowed to ignite. It is practically impossible to obtain such ignition power with electric means alone.

Experience has shown that cooled EGR rates of the order of fifty percent are possible with such a device against of the order of thirty percent only with the single most powerful electric ignition devices that are.

It will be noted that the approach adopted in the patent No. FR 2 986 564 is found in related forms in US Pat. No. 4,319,552 of the inventors Fred N. Sauer and J. Brian Barry, or in the patent No. DE 41 40 962 A1 belonging to the company "Bosch".

In any case, the patent No. US6564770 of the company "Orbital" does not fall into this category because it is according to this patent to ensure at relatively low pressure the constitution of a main load as homogeneous as possible and not to form a pilot charge for ignition of a highly diluted main charge at the EGR.

The problem of the device described by the patent No. FR 2 986 564 and in related patents as they have just been listed is not in the initialization of the combustion which is very efficient, but in the development of said combustion . In particular, when the burned fraction of the fuel contained in the main charge reaches about fifty percent, the combustion hardly progresses so that the total time required to burn the entire main charge is greater than the time required to burn the fuel. whole of an undiluted main charge to the cooled EGR. As a result, part of the potential energy gain of the cooled EGR is lost due to a combustion that develops too slowly.

However, the maximum benefit of the cooled EGR would be found if it were possible to operate a spark ignition engine simultaneously with a main charge whose cooled EGR content is of the order of fifty percent on the one hand , and with a stability and a total combustion time comparable to those found on the same said engine when the latter burns an undiluted charge on the other hand.

The solution could come from the use of a prechamber into which the pilot charge would be introduced, said prechamber being able to house the electrodes of the spark plug and even to be an integral part of said spark plug as proposed in US Pat. No. 4,319,552. The first advantage of such a prechamber is that it potentially maintains the pilot charge as close as possible to the electrodes of the spark plug, which can limit the dispersion of said charge in the main combustion chamber of the spark ignition engine before the fire of said charge.

The second advantage of said antechamber is that once ignited, the pilot charge pressurizes said prechamber which sends hot gas torches at high speed in the main combustion chamber of the spark ignition engine via orifices that includes said prechamber.

This firing of the main charge by means of torches is very effective because instead of starting from the center of the combustion chamber as is the case with an ordinary spark plug, the flame is initialized in multiple places of the combustion chamber, and develops radially from the periphery of the chamber to the center of the chamber, and tangentially between each torch.

The fuel energy is released in a very short time, which is favorable to the thermodynamic efficiency of the spark ignition engine because not only the relaxation is more productive in work, but the slightest sensitivity to rattling that results from a Such rapid combustion makes it possible to operate the engine with a significantly higher volumetric ratio.

In any event, the patent US Pat. No. 4,319,552 or the solution proposed in patent FR 2,986,564 belonging to the applicant or in the related patents previously mentioned can not be compared to the multitude of patents which inject fuel alone into a prechamber or not, and not a mixture of air and fuel.

Among these patents, mention will be made, for example, of those known under No. GB 2 31 1 327 A of "Fluid Research Limited", No. US 4,864,989 to "Tice Technology Corp.", No. 4,124,000 of "General Motors", No. 4,239,023 to "Ford Motor Company", US 4,892,070 inventor Dieter Kuhnert, No. US 2001/0050069 A1 inventors Radu Oprea and Edward Rakosi, or patent US 2012/0103302 A1 of the inventor William Attard on the principle of which is based the ignition system "Turbulent Jet Ignition" developed by the German company "Mahle" for engines of Formula 1.

There is indeed a fundamental difference between the solutions disclosed in these patents which are intended for so-called "lean-burn" spark ignition engines whose sole purpose is to enrich the fuel charge around the point of ignition. ignition on the grounds that the load as a whole is low in fuel but rich in oxygen, and the solutions set forth in patent FR 2 986 564 and related patents, which are mainly directed to positive-ignition engines operating with a heavy load. diluted with cooled EGR, which is intended to provide a fuel-rich AND oxygen-rich mixture around the ignition point, on the grounds that the fuel as a whole is low in fuel AND oxygen. At this stage, it has been seen that injecting a highly burnable pilot charge consisting of air and fuel to envelop the electrodes of the spark plug with said charge as proposed in patent No. FR 2 986 564 makes it possible to effectively light a charge. principal strongly diluted with EGR.

It has also been seen that once the main charge has been ignited, the combustion proceeds rapidly until about fifty percent of the total quantity of fuel contained in the charge has been burned. Beyond the so-called fifty percent, the combustion develops more slowly, so that from a certain EGR content of the main charge, the thermodynamic efficiency of the spark-ignition engine decreases instead of increasing as expected. .

It has been assumed that if - as proposed in US Pat. No. 4,319,552 - the pilot charge is injected into a prechamber in which the electrodes of the candle are housed, the latter problem of combustion development beyond fifty percent. would be fully or partially resolved.

In fact, said prechamber would eject through its orifices flares of hot gas with a high speed that both initialize the combustion over a great radial length around the ignition point, but also, would squint the flame front which would favor the development of the flame perpendicular to said torches.

However, this last solution may prove unsatisfactory for a large number of reasons, some of which led to abandoning ignition devices based on a prechamber, particularly in the context of spark ignition engines.

Indeed, to be effective, the prechamber must have a protruding dome which penetrates sufficiently into the combustion chamber of the engine so that the holes expelled by said dome and by which the hot gases are ejected to form torches are positioned sufficiently to interior of said chamber so that said torches do not lick the cold internal walls of said engine.

However, as soon as the combustion is initialized in the prechamber, the gases contained in the latter rise rapidly in pressure and are ejected at high speed by said holes. In doing so, said gases heat said dome.

Once the combustion of the main charge has been initiated, the pressure in the combustion chamber of the engine rapidly becomes greater than that prevailing in the prechamber so that hot gases pass through the holes of the dome in the opposite direction, again heating the latter. .

During the expansion of the gases by the piston of the spark ignition engine, the pressure prevailing in said prechamber becomes greater than that prevailing in the combustion chamber of the engine. As a result, the hot gases contained in the prechamber repass a third time through said holes, further overheating said dome. However, from a certain temperature, the protruding dome behaves like a "hot ball" like the ignition system of the internal combustion engine invented by Stuart Herbert-Akroyd and described in the patent CHD4226 of December 4 1891. Such a hot spot then potentially leads to inadvertent ignitions of the non-spark-controlled main charge. The rattling that may follow is likely to damage or even destroy the spark ignition engine.

One solution may be to intensively cool said dome to prevent it from constituting a hot spot. However, the resulting heat export is to the detriment of the efficiency of hot gas torches whose temperature and velocity are reduced when they pass through the holes in said dome, and on the other hand, the thermodynamic efficiency of the spark ignition engine.

It is therefore imperative that the prechamber can not behave like a "hot-ball" ignition device as previously mentioned or at least that the initialization of the combustion of the main charge is triggered at the chosen moment, and not suffered at an uncontrolled time.

This involves cooling the hot parts of said prechamber capable of triggering a self-ignition, but this must be done without greatly reducing the effectiveness of said prechamber to diffuse hot gas torches into the three-dimensional space of the combustion chamber of the engine that contains the main load.

In addition, it is noted that the constitution of an air-fuel pilot load carried at high pressure is not energy free. It must first compress air, which requires a compressor driven by the spark ignition engine itself, and then inject fuel into said air. Another strategy may consist in directly compressing an air-fuel mixture previously constituted. Thus, because of its non-negligible energy cost, with same ignition efficiency, the smaller the mass and the pressure of the pilot charge compared to that of the main charge, the better the final energy balance of the ignition engine. ordered when operating at high EGR rates. It is therefore necessary by all means to give the pilot load a specific efficiency to turn on the largest possible main load, relative to the weight and pressure of said pilot load.

In other words, at the same ignition efficiency, the pilot charge must contain the smallest amount of air-fuel mixture possible, previously put under the lowest possible pressure.

As such, it is necessary as far as possible to prevent the pilot charge from dispersing in the main charge before it is fired, since such dispersion reduces the specific efficiency of the pilot charge to ignite the main charge and can only be compensated for when by increasing the mass of said pilot load, which is to the detriment of the fuel efficiency of the spark ignition engine. The dispersion results in particular from the time which the injector which introduces the pilot charge into the prechamber needs to perform the injection of said pilot charge under a pressure necessarily greater than that of the main charge. It should also be noted that the injection pressure of the pilot charge remains approximately constant while the pressure of the main charge increases as a result of its compression following the raising of the piston of the spark ignition engine towards its top dead center. . The beginning of the injection of the pilot load therefore takes place under a differential pressure greater than the end of said injection. As a result, the speed of ejection of the gases constituting the pilot charge by the injector is greater at the beginning of the injection than at the end of the injection.

Before the injection of the pilot charge, the pressure in the antechamber is lower than that prevailing in the compression chamber of the engine. Part of the main load therefore first enters said prechamber as said load is compressed.

Then, the injector injects into the prechamber the pilot charge that mixes with the fraction of the main charge which has a high EGR content and which was previously introduced into said prechamber.

The excess gas mass due to said fraction is then expelled from the prechamber with a portion of the pilot charge, which is mixed with high EGR gases in and out of the prechamber.

The flammability of the mixture thus constituted of air, fuel and EGR is therefore necessarily heterogeneous in the volume of the prechamber and out of the prechamber. The efficiency of the pilot charge to ignite as quickly as possible is reduced as well as the effectiveness of the flaming gas torches to ignite the main charge.

This decrease in efficiency can only be offset by an increase in the air and fuel mass of the pilot load, to the detriment of the overall energy efficiency of the spark ignition engine. Ideally, it should therefore be avoided by any means to disperse the pilot charge in the main charge before the ignition of said pilot charge.

This does not call into question the fact that it would be very advantageous to improve the device described by the patent No. FR 2 986 564. In fact, said device has been effective in initiating the combustion at very high rates of EGR cooled and develop said combustion until a fraction of about fifty percent of the fuel contained in the main charge is burned.

The objective would be to give the device the ability to develop said combustion very rapidly until a fraction of at least ninety or one hundred percent of said fuel is burned. As previously mentioned, this could be achieved by means of a prechamber as suggested by US Pat. No. 4,319,552, but with the sole condition of circumventing the notorious or even crippling defects of such a prechamber. For this, it is necessary to significantly improve the efficiency of said prechamber which includes avoiding that it behaves like a "hot ball", to prevent the pilot charge is dispersed in the main chamber, and limit the amount of energy required to compress said pilot charge to same ignition efficiency.

All of these objectives are addressed by the ignition prechamber valve according to the invention which - according to a particular embodiment - allows:

• To greatly reduce the thermal load to which the protruding dome exposed by the prechamber is subjected, this by dividing by approximately three the number of passages of the hot gases through the holes of said dome and through which said gases are ejected, and this in order to prevent said dome from being raised to too high a temperature and constitutes a hot spot liable to cause untimely self-ignition of the main charge;

• To minimize the mass and the pressure of the pilot charge necessary not only for the initialization of the combustion of highly diluted main charges at the EGR, but also for the rapid development of said combustion until all of said charges main ones are burned;

• In the service of this last objective, to avoid the dispersion of the pilot load in the main load during the injection of said pilot load in the prechamber.

To achieve these objectives, the ignition pre-ignition chamber according to the invention provides:

• Keep the prechamber closed when the pressure therein is lower than that prevailing in the combustion chamber, in order to avoid inadvertent back and forth of the hot gases through the holes in the protruding dome and through which said prechamber communicates with said chamber;

• Keep the prechamber closed during most of the injection time of the pilot load so that said injection takes place in a closed space in which the gases of said pilot charge can not mix with the gases of the charge principal;

• Lowering the mass and injection pressure of the pilot charge while maintaining high exhaust gas pressure and velocity through the holes in the protruding dome.

The pre-ignition valve chamber is cheap cheap to manufacture in large series to remain compatible with the economic constraints of most applications for which it is intended, including automobiles. It is understood that the valve ignition prechamber according to the invention can be applied to any rotary ignition engine or internal combustion irrespective of the type, regardless of the gaseous fuel, liquid or solid that it consumes, and that its main charge is diluted with EGR cooled or not, with a neutral gas of any nature whatsoever, or with a gas rich in oxygen or any other oxidant.

It is also understood that the pilot charge that receives the valve ignition prechamber according to the invention may contain a fuel and / or oxidant different from the fuel and / or oxidant which constitutes the main charge of the spark ignition engine.

The other features of the present invention have been described in the description and in the dependent claims directly or indirectly dependent on the main claim. The ignition prechamber according to the present invention is provided for an internal combustion engine which comprises a cylinder head which caps a cylinder to form a combustion chamber in which a main charge can be burned, said prechamber comprising: · At least one stratification cavity which is firstly arranged in the cylinder head and is connected to the combustion chamber by a stratification duct and which, on the other hand, receives a lamination injector which can directly or indirectly inject into said cavity a charge pilot previously pressurized by compression means, said load consisting of an AF fuel-fuel mixture easily ignitable by means of a spark;

• ignition means that open into the lamination cavity and can ignite the pilot charge; · A laminating valve which can seal all or part of the lamination duct and which exposes, on the one hand, a cavity-side face subjected to the pressure of the gases prevailing in the lamination cavity and, on the other hand, a chamber-side face subjected to the pressure of the gases prevailing in the combustion chamber, said laminating valve being able to translate with respect to said duct under the effect of the pressure of the gases either towards the lamination cavity when said pressure prevailing in the latter is less than the pressure prevailing in the combustion chamber, towards said chamber when the pressure in the latter is lower than the pressure in the lamination cavity; · At least one cavity-side check stopper that determines the position of the laminating valve closest to the laminating cavity;

• At least one chamber-side check stopper that determines the position of the laminating valve closest to the combustion chamber. The valve ignition pre-chamber according to the present invention comprises a laminating valve which closes all or part of the lamination duct when it is closer to the lamination cavity while it opens said duct on a larger section when positioned closest to the combustion chamber.

The valve ignition prechamber according to the present invention comprises a cavity-side valve stop which consists of a valve closure seat arranged in the lamination duct or at any of the ends of said duct, said cooperating seat. with a cavity-side valve seat that the lamination valve has at its periphery and / or at its end.

The valve ignition prechamber according to the present invention comprises a valve closure seat and a cavity-side valve seat which constitute a seal when in contact with each other, said sealing preventing any gas from passing through. at said contact when the pressure in the combustion chamber is greater than the pressure in the lamination cavity.

The valve ignition prechamber according to the present invention comprises a chamber-side valve stop which consists of a valve opening seat arranged in the lamination duct or at any of the ends of said duct, said cooperating seat with a chamber-side valve seat that the laminating valve has at its periphery and / or at its end.

The valve ignition prechamber according to the present invention comprises a valve opening seat and a chamber-side valve seat which provide a seal when in contact with each other so as to prevent any gas from passing through. at the level of said contact.

The valve ignition prechamber according to the present invention comprises a laminating valve which comprises in its periphery guiding means which maintain said valve approximately centered in the lamination duct, and approximately in the same longitudinal orientation as said duct and this, regardless of the axial position of said valve relative to said conduit. The valve ignition prechamber according to the present invention provides that when the valve opening seat and the chamber side valve seat are in contact with each other, the laminating valve forms with the laminating duct a torch ignition prechamber which communicates simultaneously with the lamination cavity and with the combustion chamber via at least one gas ejection port.

The valve ignition pre-chamber according to the present invention comprises an inner peripheral wall of the ignition prechamber torch which is cylindrical while the laminating valve has a circular periphery and is housed with a small radial clearance in said prechamber. The valve ignition pre-chamber according to the present invention comprises a lamination duct which projects into the combustion chamber in the form of a protruding ejection dome which houses the ignition prechamber and from which opens the flare gas ejection port.

The valve ignition pre-chamber according to the present invention comprises a valve opening seat which is arranged in the protruding ejection dome.

The ignition pre-ignition valve according to the present invention provides that when the laminating valve is positioned close to the combustion chamber that is to say in the vicinity or in contact with the chamber-side valve stopper with which it cooperates, said valve discovers at least one gas ejection port that connects the lamination cavity with the combustion chamber. The ignition pre-ignition chamber according to the present invention comprises ignition means which consist of a spark plug which closes the first end of a perforated connecting tube which traverses all or part of the internal volume of the cavity layer and whose body is radially traversed by at least one radial lumen which connects the interior of said tube with said internal volume, while the second end of said tube receives the lamination duct and the laminating valve, and yet that the central electrode and the ground electrode of said spark plug are housed inside the perforated connecting tube.

The ignition prechamber according to the present invention comprises a cavity-side face which exposes an aerodynamic dome.

The ignition prechamber valve according to the present invention comprises a cavity-side face which forms a ground electrode which faces a central electrode that comprises a spark plug the latter constituting the ignition means.

The valve ignition prechamber according to the present invention comprises a laminating valve which is axially thicker at its periphery which receives the cavity-side valve seat and the chamber-side valve seat than at its center. The following description with reference to the accompanying drawings and given by way of non-limiting example will better understand the invention, the features it has, and the benefits it is likely to provide:

Figure 1 is a schematic sectional view of the ignition prechamber valve according to the invention as it can be installed in the cylinder head of an internal combustion engine.

Figure 2 is a schematic sectional view of the valve ignition prechamber according to the invention, the laminating valve can completely close the lamination duct when the cavity-side valve seat that has said lamination valve is in contact with the seat shutter valve with which it cooperates, while said laminating valve forms a pre-ignition chamber by torch which is housed in a protruding ejection dome when said valve rests on its chamber-side valve stop. Figures 3 to 8 are partial close-up views in schematic section of the ignition prechamber valve according to the invention and according to the particular configuration shown in Figure 2, said close-up views illustrating various phases of operation of said prechamber.

Figure 9 is a schematic sectional view of the ignition prechamber valve according to the invention incorporating the main features shown in Figure 2 to which is added a radially perforated connecting tube traversed by radial lumens, said tube passing through the internal volume of the lamination cavity and forming an integral part of a spark plug, while the cavity-side face of the lamination valve forms a ground electrode which faces a central electrode that includes said spark plug.

FIG. 10 is a three-dimensional view of the ignition prechamber with a flap according to the invention and according to the variant embodiment shown in FIG. 9.

Figure 1 1 is a three-dimensional view in broken longitudinal section of the ignition prechamber valve according to the invention and according to the embodiment shown in Figure 9.

Figure 12 is an exploded three-dimensional view of the ignition prechamber valve according to the invention and according to the embodiment shown in Figure 9.

DESCRIPTION OF THE INVENTION

Figures 1 to 12 show the valve ignition prechamber 1, various details of its components, its variants, and its accessories.

FIG. 1 shows that the valve ignition pre-chamber 1 is specially designed for an internal combustion engine 2 which comprises a cylinder head 3 which caps a cylinder 4 to form a combustion chamber 5 with a piston 31 in which it can be burned a main charge 30.

It will be noted in FIGS. 1 to 12 that the valve ignition prechamber 1 according to the invention comprises at least one lamination cavity 6 which, on the one hand, is arranged in the cylinder head 3 and is connected to the combustion chamber 5 by a lamination duct 7 and which, on the other hand, receives a lamination injector 8 which can directly or indirectly inject into said cavity 6 a pilot load 9 previously pressurized by compression means 10.

The pilot charge 9 is, according to the invention, constituted by an AF fuel-fuel mixture that is highly flammable by means of a spark.

In FIGS. 1, 2 and 9, the lamination injector 8 provided by the valve ignition pre-chamber 1 according to the invention and which can, directly or indirectly via an injector outlet duct 28, inject the charge pilot 9 in the lamination cavity 6. The lamination injector 8 may be of any type without restriction, and may consist of any apparatus capable of introducing into the lamination cavity 6 according to any operating procedure whether it be a pilot charge 9 and this, that the fuel-fuel mixture AF that contains said charge 9 is formed upstream or downstream of said lamination injector 8 with the possible assistance of another injector either gas or liquid, or with the assistance of a carburetor known per se.

In addition, the lamination cavity 6 and the lamination duct 7 can advantageously be coated with a refractory material known per se, or be made of said material. Alternatively, an air gap may be left between at least a portion of the lamination cavity 6 and / or the lamination duct 7, and the yoke 3 which receives these components 6, 7 of FIG. on the other hand, so as to limit heat exchanges between said components 6, 7 and said cylinder head 3. It can also be seen in FIGS. 1 to 12 that the valve ignition prechamber 1 according to the invention comprises ignition means 1 1 which open into the lamination cavity 6 and which can ignite the pilot charge 9, said means 1 1 may consist of a spark plug 12 known per se. Still in FIGS. 1 to 12, it will be noted that the valve ignition prechamber 1 according to the invention comprises a laminating valve 13 which can seal in all or part of the laminating duct 7 and which exposes, on the one hand, a single face cavity side 14 subjected to the pressure of the gases prevailing in the lamination cavity 6 and secondly, a chamber side face 15 subjected to the pressure of the gases prevailing in the combustion chamber 1 January.

It is noted that said laminating valve 13 can translate with respect to the stratification duct 7 under the effect of the pressure of the gases either towards the lamination cavity 6 when said pressure prevailing therein is lower than the pressure prevailing in the laminating cavity. combustion chamber 5, in the direction of said chamber 5 when the pressure prevailing therein is lower than the pressure prevailing in lamination cavity 6.

Note that the laminating valve 13 can also move in the lamination duct 7 under the effect of gravity or acceleration, which can not be interpreted as any advantage or a desired mode of operation.

It can be emphasized that the laminating valve 13 may be made of a temperature-resistant superalloy and remain as light as possible, or of a ceramic material such as silicon carbide.

In addition to what has just been described, it will be noted that the valve ignition pre-chamber 1 according to the invention comprises at least one cavity-side valve stop 16 which determines the position of the laminating valve 13 closest to the cavity of the invention. 6. This is particularly visible in Figures 3 to 8. In addition, the valve ignition pre-chamber 1 according to the invention comprises at least one chamber-side valve stop 17 which determines the position of the laminating valve 13 closest to the combustion chamber 5. As a variant of the valve 1 ignition chamber according to the invention, it will be noted that the laminating valve 13 may close all or part of the lamination duct 7 when it is closest to the lamination cavity 6 while it opens said duct 7 over a wider section when it is positioned closer to the combustion chamber 5.

In FIGS. 3 to 8 in particular, it will be noted that the cavity-side valve stop 16 may consist of a valve closure seat 18 provided in the laminating duct 7 or at any of the ends of said duct 7, said seat 18 cooperating with a cavity-side valve seat surface 19 that the laminating valve 13 presents at its periphery and / or at its end.

It should also be noted that the shutter valve seat 18 and the cavity-side valve seat 19 may constitute a seal when they are in contact with each other, said sealing preventing any gas from passing to the level of said contact when the pressure in the combustion chamber 5 is greater than the pressure in the lamination cavity 6.

As another variant, the chamber-side valve stop 17 may consist of a valve opening seat 20 arranged in the laminating duct 7 or at any of the ends of said duct 7, said seat 32 cooperating with a chamber-side valve seat 21 that the laminating valve 13 has at its periphery and / or at its end.

In this case, the valve opening seat 20 and the chamber-side check valve seat 21 may provide a seal when in contact with each other so as to prevent any gas from passing at said contact.

FIGS. 3 to 8 and FIG. 12 clearly show that the laminating valve 13 may comprise in its periphery guide means 22 which hold said valve 13 approximately centered in the laminating duct 7, and approximately in the same longitudinal orientation as said duct 7 and this, regardless of the axial position of said valve 13 with respect to said duct 7.

In FIGS. 2, 3, 6, 8 and 9, it will be noted that when the valve opening seat 20 and the chamber-side valve bearing surface 21 are in contact with each other, the laminating valve 13 can form with the laminating duct 7 a torch ignition prechamber 23 which simultaneously communicates on the one hand with the laminating cavity 6 and on the other hand with the combustion chamber 5 via at least one gas ejection port 24. In this particular context of the ignition prechamber valve 1 according to the invention, the inner peripheral wall of the ignition prechamber torch 23 may be cylindrical while the laminating valve 13 has a circular periphery and is housed low radial clearance in said prechamber 23 so that a small radial clearance is left between said valve 13 and said wall regardless of the position of said valve 13 relative to said prechamber 23, said small clearance forming a restricted passage which slows down the passage of gas between the lamination cavity 6 and the combustion chamber 5.

FIGS. 1 to 12 show that according to a particular embodiment of the valve ignition prechamber 1 according to the invention, the lamination duct 7 can project into the combustion chamber 5 in the form of a dome protruding ejection 25 which houses the ignition pre-ignition chamber 23 and which opens the gas ejection orifice 24. It is noted that the gas ejection orifice 24 may be more or less oriented towards the chamber of combustion 5 and exit more or less tangentially to the periphery of the protruding ejection dome 25. In addition, the geometry of the gas ejection orifice 24 may vary depending on whether the jet of gas leaving said orifice 24 is provided rather directional , or rather diffuse. For example, the gas ejection orifice 24 may be cylindrical, conical, or form a convergent or a divergent.

Advantageously and as shown in Figures 1 to 12, the valve opening seat 20 can be arranged in the protruding ejection dome 25, the latter can be coated with antifriction material and / or non-stick and / or refractory known per se, or be made of said material.

In the general sense, it is understood that when the laminating valve 13 is positioned close to the combustion chamber 5, that is to say in the vicinity or in contact with the chamber-side valve stop 17 with which it cooperates, said valve 13 can uncover at least one gas ejection port 24 which connects the lamination cavity 6 with the combustion chamber 5.

As can be seen in FIGS. 9 to 12, the ignition means 11 may consist of a spark plug 12 which closes the first end of a perforated connecting tube 26 which passes all or part of the internal volume of the lamination cavity 6 and whose body is radially traversed by at least one radial slot 27 which connects the inside of said tube 26 with said internal volume, while the second end of said tube 26 receives the lamination duct 7 and the valve lamination 13, and while the central electrode 40 and the ground electrode 39 of said spark plug 12 are housed inside the perforated connecting tube 26.

Note in Figures 9 to 12 that the perforated connecting tube 26 may be part of the spark plug 12 which it extends the base. In this case, the spark plug 12 is directly screwed into the cylinder head 3 by means of a threading formed on the outer cylindrical face of its base and / or on the outer cylindrical face of the perforated connecting tube 26 which extends it. Alternatively, the spark plug 12 can be screwed into said tube 26 while the latter is screwed into the cylinder head 3. In all cases, a seal is made between the yoke 3 on the one hand and the candle 12 and / or the perforated connecting tube 26 on the other hand, both at the level of said spark plug 12 and at the lamination duct 7.

FIGS. 9 to 12 illustrate that the cavity-side face 14 can expose an aerodynamic dome 29 which makes it possible, in particular, to direct the flow of gas towards the gas ejection opening (s) 24 by offering the said flow as little resistance as possible and by generating in said flow the least possible turbulence.

FIGS. 1 to 12 show that according to a particular embodiment of the valve ignition prechamber 1 according to the invention, the cavity-side face 14 can form a ground electrode 39 which faces a central electrode 40 that comprises a spark plug 12 the latter constituting the ignition means 1 1, an electric arc can be formed between said ground electrode 39 and said central electrode 40 when a high-voltage current passes from said central electrode 40 to said electrode of mass 39.

Figures 1 to 12 further illustrate that the laminating valve 13 may be axially thicker at its periphery which receives the cavity-side valve seat 19 and the chamber-side valve seat 21, than at its center.

This feature gives said valve 13 a radial thickness which increases from the center of said valve 13 towards the periphery of the latter, so that said valve 13 is both the lightest possible and the most resistant to possible shocks, while ensuring its cooling most effectively possible at the contact between its valve seats 19, 21 and the seats 18, 20 with which cooperate said bearing surfaces 19, 21.

OPERATION OF THE INVENTION: The operation of the ignition prechamber valve 1 according to the invention is easily understood in the light of Figures 1 to 12.

It can be seen that according to the nonlimiting example of application of the ignition pre-ignition chamber 1 according to the invention shown in FIG. 1, said prechamber 1 is implemented in an internal combustion engine 2 which comprises a cylinder head 3 which cap a cylinder 4 to form with a piston 31 a combustion chamber 5 in which can be burned a main charge 30.

Note that the piston 31 is connected to a crankshaft 37 via a connecting rod 38, said piston 31 printing said crankshaft 37 a rotational movement when said piston 31 is driven by an alternating translational movement in the cylinder 4 .

FIG. 1 also shows that the combustion chamber 5 can be placed in communication with an intake duct 32 via an intake valve 34 while said chamber 5 can be placed in communication with an exhaust duct 33 by means of a exhaust valve 35. FIGS. 1 to 8, which will be taken here as examples to illustrate the operation of the valve ignition prechamber 1 according to the invention, show that said antechamber 1 is integrated with the cylinder head 3. Said FIGS. 1 to 8 also show that the ignition means 1 1 here consist of a spark plug 12 known per se and whose electrodes open into the lamination cavity 6. Note also in FIGS.

2 the lamination injector 8 which can inject a pilot charge 9 into the lamination cavity 6 via an injector outlet duct 28.

It can be seen in FIG. 1 that, prior to its injection by the stratification injector 8, the pilot charge 9 consisting of an easily flammable fuel-oxidant mixture AF has been pressurized by a laminating compressor 36 which forms the compression means 10. This is also a non-limiting example of embodiment of the ignition prechamber valve 1 according to the invention, taken here by way of example to illustrate the operation.

To illustrate the operation of the ignition pre-ignition chamber 1 according to the invention, we will assume here that the volumetric ratio of the internal combustion engine 2 - out of volume of the ignition pre-ignition chamber 1 - is fourteen to one. To obtain this result, a volume swept by the piston 31 of five hundred cubic centimeters is provided while the volume of the combustion chamber 5 is thirty eight decimal five cubic centimeters.

In addition and by way of nonlimiting example, the volume of the ignition pre-ignition chamber 1 - including the volume of the laminating duct 7 and that of the injector outlet duct 28 - here is half cubic centimeter.

To detail the operation of the ignition prechamber valve 1 according to the invention, we will retain here the embodiment shown in Figures 1 to 8 on which it is found that the cavity-side valve stop 16 consists of a shutter seat valve 18 arranged in the lamination duct 7, said seat 18 cooperating with a cavity-side valve seat 19 that has the lamination valve 13 at its periphery.

It has been chosen here that the valve closing seat 18 and the cavity-side valve seat 19 form a seal when in contact with each other, said sealing preventing any gas from passing at said contact when the pressure prevailing in the combustion chamber 5 is greater than the pressure prevailing in the lamination cavity 6.

Note also that to illustrate the operation of the ignition prechamber valve 1 according to the invention, it has also been provided that the chamber-side valve stop 17 consists of a valve opening seat 20 arranged in the conduit laminating member 7, said seat 32 cooperating with a chamber-side valve seat 21 that the laminating valve 13 has at its periphery. This particular configuration is clearly visible in figures

3 to 8. In this particular context, it will be provided that the valve opening seat 20 and the chamber-side valve seat 21 provide a seal when in contact with each other so as to prevent any gas from passing through the chamber. said contact. Particularly in FIGS. 2, 3, 6 and 8, it will also be appreciated that when the valve opening seat 20 and the chamber side valve seat 21 are in contact with each other, the laminating valve 13 forms with the laminating duct 7 an annular ignition pre-chamber 23 of annular form, said pre-chamber 23 simultaneously communicating on the one hand with the lamination cavity 6, and on the other hand with the combustion chamber 5 via several gas ejection ports 24.

Note also that the inner peripheral wall of the ignition prechamber torch 23 is cylindrical while the laminating valve 13 has a circular periphery and is housed at low radial clearance in said prechamber 23 so that a small radial clearance is left between said valve 13 and said wall regardless of the position of said valve 13 with respect to said prechamber 23, said small clearance forming a restricted passage which brakes any passage of gas - via said small clearance - between the lamination cavity 6 and the combustion chamber 5. It is also noted in Figures 1 to 8 that the lamination duct 7 opens projecting into the combustion chamber 5 in the form of a protruding ejection dome 25 which houses the pre-ignition chamber by torch 23 and which open out the gas ejection orifices 24 which, according to this example, are oriented towards the combustion chamber 5. It will be noted in passing that the seat of open Valve 20 is arranged in the protruding ejection dome 25.

Incidentally, it should be noted in FIGS. 1 to 8 that the cavity-side face 14 of the laminating valve 13 exposes an aerodynamic dome 29 which makes it possible, in particular, to direct the flow of gas towards the gas ejection orifices 24 by offering the said flow the least amount of gas. resistance and generating in said flow the least possible turbulence.

It is also noted that the laminating valve 13 is axially thicker at its periphery than at its center. This feature allows said valve 13 to be both the lightest possible and the most resistant to possible shocks, while ensuring its cooling as effectively as possible a level of contact between its valve seats 19, 21 and the seats 18, 20 with which cooperate said bearing surfaces 19, 21. By way of non-limiting example, the laminating valve 13 can be made in a mechanically and thermally highly resistant superalloy. According to the embodiment of the ignition prechamber valve 1 according to the invention shown in Figures 1 to 8 and taken here as an illustration of the operation of said prechamber 1, we consider that the diameter of the ejection orifices gas 24 is equal to twelve hundredths of a millimeter while the maximum total travel that can traverse the laminating valve 13 between the shutter valve seat 18 and the valve opening seat 20 is worth fifteen hundredths of a millimeter. To understand the operation of the ignition prechamber valve 1 according to the invention, it is useful here to break down the operation during the four stages of the internal combustion engine 2, in connection with Figures 3 to 8. Consider that the internal combustion engine 2 operates with a substantially stoichiometric main air-fuel charge substantially diluted by cooled recirculated exhaust gases known as "cooled EGR". Said charge 30 is therefore resistant to ignition and is in no way conducive to rapid development of its combustion in the three-dimensional space of the combustion chamber 5.

As such, it is expected that the pilot charge 9 which will be implemented by the valve ignition prechamber 1 according to the invention must have the greatest possible efficiency not only to initialize the combustion of the main charge 30, but also to develop said combustion in the shortest possible time. It is understood that these two objectives are directly served by the ignition prechamber valve 1 according to the invention.

According to the nonlimiting example embodiment of the valve ignition prechamber 1 according to the invention taken here to illustrate its operation, we will assume that the pilot charge 9 contains a comma six percent of the fuel contained in the main charge. , said pilot charge 9 consisting of an AF fuel-fuel mixture that is highly flammable by means of a spark.

Here we will decompose the four-stroke cycle of Otto or Beau de Rochas according to the usual sequencing.

In the intake phase, the piston 31 of the internal combustion engine 2 descends into the cylinder 4 with which it cooperates, which has the effect of introducing into the latter a main charge 30 coming from the intake duct 32 and via the intake valve 34 kept open.

During said phase, the pressure prevailing in the combustion chamber 5 is lower than the pressure that prevails in the lamination cavity 6. As a result and as shown in FIG. 3, the laminating valve 13 remains plated on the seat of FIG. valve opening 20 with which it cooperates and the lamination cavity 6 is placed in communication with the combustion chamber 5 through the gas ejection ports 24 via the torch ignition pre-chamber 23.

The piston 31 having reached its low dead point, the valve the inlet valve 34 closes and the piston 31 begins its ascent in the cylinder 4, to its top dead center.

In doing so, said piston 31 compresses the main charge 30 and the pressure prevailing in the combustion chamber 5 becomes higher than that prevailing in the lamination cavity 6. The pressure difference between said chamber 5 and said cavity 6 increases all the more rapidly as, on the one hand, the section of the gas ejection orifices 24 is small and, on the other hand, a small radial clearance is left between the stratification valve 13 and the inner wall of the ignition pre-chamber by torch 23, regardless of the position of said valve 13 relative to said prechamber 23.

To go from the combustion chamber 5 to the lamination cavity 6, the gases constituting the main charge 30 have virtually no other passage than that constituted by the gas ejection orifices 24.

The latter leaving only a passage section limited to said gases, the difference between the pressure exerted on the cavity side face 14 and that exerted on the chamber side face 15 increases, which has the effect of pressing the laminating valve 13 on the shutter valve seat 18 with which it cooperates. This situation is clearly illustrated in Figure 4.

It will be noted that the time required for the laminating valve 13 to firstly break the contact that it forms with the valve opening seat 20 with which it cooperates and secondly to come into contact with the seat. shutter 18, is worth a few degrees of rotation of the crankshaft 37 or even one or two degrees only of said rotation, these values being given only as an indication.

In doing so, the laminating valve 13 closes the lamination duct 7 and the combustion chamber 5 no longer communicates with the lamination cavity 6. The pressure which continues to increase in the combustion chamber 5 due to the rise of the piston 31 in the cylinder 4 has no further effect on the pressure in the lamination cavity 6, said pressure remaining stable.

A few degrees of crankshaft after the laminating valve 13 has closed the lamination pipe 7, the lamination injector 8 begins to inject the pilot charge 9 into the lamination cavity 6. This situation is illustrated in FIG. constituent gases of said charge 9 is according to this example of the order of eighty degrees.

The flow rate of the injector has been calculated so that the pressure in the lamination cavity 6 remains always lower than that which prevails in the combustion chamber 5 so that the laminating valve 13 never takes off from the seat. shutter valve 18 with which it cooperates via its valve seat side cavity 19.

A few degrees of crankshaft 37 before the top dead center of the piston 31, the pressure prevailing in the combustion chamber 5 and to which the main load 30 is subjected has reached nearly forty bar while the pressure in the lamination cavity 6 has reached twenty bars. The lamination injector 8 stops injecting the pilot charge 9 into the lamination cavity 6.

The piston 31 arriving in the vicinity of its Top Dead Center and as shown in Figure 6, a high-voltage current is applied across the spark plug 12. The latter ignites the pilot charge 9 contained in the cavity of stratification 6. It will be noted moreover that the pressure of only twenty bar prevailing in said cavity 6 allowed to apply only a moderate tension across the spark plug 12.

As shown in FIG. 6, since the pilot charge 9 consists of a highly flammable AF comburent-fuel mixture, the flame initialized by the spark plug 12 propagates very rapidly in the pilot charge 9, the temperature of which increases just as rapidly. , as well as the pressure in the lamination cavity 6.

When said pressure reaches for example forty five bars - that is to say five bars more than the pressure prevailing in the combustion chamber 5, the stratification valve 13 has already traveled fifteen hundredths of a millimeter. In doing so, said valve 13 took off from its contact with the shutter valve seat 18, then came to rest on the valve opening seat 20. This situation is also shown in Figure 6. During its journey, the laminating valve 13 has gradually discovered the gas ejection orifices 24, and the hot gases from the lamination cavity 6 - which have been, for example, brought to a temperature of about two thousand degrees Celsius - have begun to be ejected in the form of torches by said orifices 24, via the ignition prechamber torch 23, and at the protruding ejection dome 25. This figure is illustrated by this effect provided by the ignition pre-ignition chamber 1 according to the 'invention.

As the pressure continues to rise in the lamination cavity 6, the pressure in said cavity 6 is now twenty bars greater than that prevailing in the combustion chamber 5. As a result, the hot gases have their pressure drop by 20 bar when they are heated. passing through the gas ejection orifices 24 so that their temperature falls around one thousand three hundred degrees. In return, said gases are animated with a high speed which allows them to penetrate deeply into the volume of the combustion chamber 5. In doing so, said hot gases ignite the surrounding gases constituting the main charge 30. In addition release in form heat of the energy of the fuel they contain, said surrounding gases are found animated by a high local velocity by said hot gases, said velocity materializing in the form of micro turbulence. The folding of the flame front resulting from said micro turbulence promotes the development of combustion, which propagates rapidly to the entire main charge 30 and in the entire volume of the combustion chamber 5.

It will be noted that the effectiveness of the ignition pre-ignition chamber 1 according to the invention in developing the said combustion is all the greater as the hot gas torches formed around the protruding ejection dome 25 ignite the charge. main 30 in multiple places of the combustion chamber 5.

Indeed, once initialized radially from the center to the periphery of the combustion chamber 5, the combustion of said load 30 develops in a second phase radially from the periphery of said chamber 5 towards the center of said chamber 5, and tangentially between each flaming gas torch coming out of the ejection dome protruding through the gas ejection ports 24. Once the combustion-fuel mixture AF constituting the pilot charge 9 completely burned and largely ejected in the form of hot gas jets via the gas ejection orifices 24, combustion develops in the combustion chamber 5 and the pressure prevailing in the latter quickly becomes greater than that prevailing in the lamination cavity 6.

Also, as soon as this situation is reached, the chamber-side face 15 of the stratification valve 13 receives a pressure greater than that which is exerted on the cavity-side face 14 of the valve 13. This results from the fact that the laminating valve 13 moves quickly fifteen hundredths of a millimeter towards the lamination cavity 6, and is pressed tightly on the shutter valve seat 18 with which it cooperates. This situation is illustrated in FIG. 7. Since the combustion of the main charge 30 operates very rapidly despite the high content of "cooled EGR" of the said charge 30, the said combustion is completed only a few degrees of crankshaft 37 after the Top Dead Center of the piston 31. The thermodynamic efficiency of the internal combustion engine 2 will thus be able to be maximum because the trigger has barely started while the entire energy contained in the fuel constituting the main charge 30 has been released.

As the laminating valve 13 remains closed as illustrated in FIG. 7, the piston 31 then starts its expansion stroke and begins to transform into work a large part of the heat of the hot and burned gases of the main charge 30. Said work is transmitted to the crankshaft 37 by said piston 31 via the connecting rod 38.

In doing so, the pressure and the temperature prevailing in the combustion chamber 5 gradually decreases. When said pressure reaches for example sixty bar, the pressure remaining in the lamination cavity 6 becomes greater than that prevailing in the combustion chamber 5.

As a result of this situation, the chamber-side valve seat 21 of the laminating valve 13 returns to contact with the valve opening seat 20, as illustrated in FIG. 8. The laminating valve 13 again completely uncovers the ejection of the gases 24 and the residual hot gases of the pilot charge 9 are ejected via said orifices 24 to be expanded by the piston 31, at the same time as the expansion of the main charge 30 is continued.

Once the piston 31 has reached its lowest dead point, the exhaust valve 35 opens and the gases finish to relax in the exhaust duct 33 before being actively discharged by said piston 31 into said duct 33 when said piston 31 rises in the cylinder 4 towards its top dead center.

Throughout the exhaust stroke of the piston 31, the lamination cavity 6 can finish expelling residual hot gases from the pilot charge 9 via the gas ejection ports 24. This expulsion can also continue during the admission phase which marks the start of a new four-stroke cycle of Otto or Beau de Rochas according to the usual sequencing. As can be seen throughout the explanation just given, unlike known devices according to the state of the art, the ignition prechamber valve 1 according to the invention has limited pressure injecting the pilot charge 9 at approximately twenty bars. This relatively low pressure has not only made it possible to limit the energy consumption of the laminating compressor 36, but also to limit the complexity thereof in that a single compression stage was sufficient to reach said pressure.

In addition, only one point six percent of the fuel contained in the main charge 30 was sufficient to provide a powerful ignition of said load 30 - of the order of two hundred times more powerful than a conventional spark ignition, said ignition having taken place in multiple locations homogeneously distributed in the three-dimensional space of the combustion chamber 5. The low compression pressure of the pilot charge 9 on the one hand, and the small amount of AF comburent-fuel mixture contained in said load 9, on the other hand, both of them have contributed to minimizing the energy consumed by the laminating compressor 36 to compress said pilot load 9. This has thus made it possible to minimize the amount of work that the laminating compressor 36 has directly or indirectly punctured on the crankshaft 37 of the internal combustion engine 2, which contributed to maximize the final energy efficiency of said engine 2.

In addition, it will be noted that the time allowed for the lamination injector 8 to inject the pilot charge 9 into the lamination cavity 6 has been almost equivalent to the time allocated to the compression phase of the internal combustion engine 2 according to the cycle at four beats of Otto or Beau de Rochas. This made it possible, on the one hand, to limit the dynamics sought for said injector 8, and on the other hand, to limit the supply pressure of said injector 8. This contributes in particular to reducing the cost and the complexity of said injector 8 while giving it better reliability, and great durability.

During the entire duration of the injection of the pilot charge 9 into the lamination cavity 6, it will be noted that said charge 9 has been mixed with only a small amount of residual flue gases. The content of said flue gases from said charge 9 before its spark ignition was only about one per thousand, which is extremely low.

As a result of this, the pilot charge 9 has maintained a maximum flammability which, combined with a pressure of only 20 bar when the spark plug 12 ignited said charge 9, has made it possible to limit the voltage to be applied across the terminals. of said spark plug 12 to obtain said firing. This results in a lower power consumption to power said candle 12, and increased durability of the latter. It will be noted that during the sequence of operation illustrated in successive steps from Fig. 3 to Fig. 8, the thermal load applied to the protruding ejection dome 25 has been reduced to a bare minimum in that the gases raised to high temperature have passed through the gas ejection orifices 24 only once, compared to three for any prechamber according to the state of the art, such prechamber being devoid of laminating valve 13.

This particularity has notably made it possible to prevent said dome from rising to too high a temperature and forming a hot spot liable to cause untimely and uncontrolled ignitions of the main charge leading to rattling and to the damage or even the In addition, this propensity of the protruding ejection dome 25 to remain at low temperature makes it possible to provide a high compression ratio for the internal combustion engine 2, without the risk of knocking.

Thus, the valve ignition prechamber 1 according to the invention makes it possible to produce internal combustion engines 2 with controlled ignition operating under a high rate of cooled EGR, whatever the load and the speed of rotation of said engines 2, and without compromising the combustion stability of these.

As a result of said high rate of EGR, the intake pressure of said engines 2 is naturally higher at partial loads than that of internal combustion engines 2 of the same design operating without cooled EGR. This reduces the pumping losses caused by the adjustment of the load by the intake pressure, said adjustment being for example operated by means of a butterfly.

In addition, the internal combustion engines 2 receiving the ignition prechamber valve 1 according to the invention have their thermal losses reduced, as is the amount of nitrogen oxides per kilowatt hour produced by said engines 2. This results from the fact that the combustion of the main charge 30 takes place at a lower average temperature thanks to the possibility offered by the ignition prechamber valve 1 according to the invention to introduce EGR cooled strong. proportions in said load 30.

In this context allowed by the valve ignition prechamber 1 according to the invention, the compression ratio of the internal combustion engines 2 can be expected to be higher than that of the said two operating engines without cooled EGR and this, without risk of rattling. This is favorable to the performance of said engines 2.

It will further be noted that the reduction in pumping losses and thermal losses induced by the valve ignition pre-chamber 1 according to the invention makes it less necessary to significantly reduce the displacement of the internal combustion engines 2 to iso-torque and iso-torque. -power by adding a supercharging, for example by turbocharger. Indeed, the supercharging may be either reduced or non-existent while maintaining high energy performance vis-à-vis the state of the art. As a result of this set of characteristics and advantages conferred by the valve ignition prechamber 1 according to the invention, the internal combustion engines 2 are at moderate cost, with low fuel consumption and with low carbon dioxide emissions. , and whose post-treatment of pollutants is ensured by a simple three-way catalyst.

Note that it can not be ruled out that the ignition prechamber valve 1 according to the invention can be applied to other areas that only internal combustion engines. Said antechamber 1 can for example be applied to gas nailers, firearms, or any device requiring the firing of a main load by means of a pilot load with the best possible efficiency.

The possibilities of the ignition prechamber valve 1 according to the invention are not limited to the applications just described and it must also be understood that the foregoing description has been given only to as an example and that it does not limit the field of said invention which one would not go out by replacing the execution details described by any other equivalent.

Claims

Valve ignition antechamber (1) for an internal combustion engine (2) which comprises a cylinder head (3) which caps a cylinder (4) to form a combustion chamber (5) in which a main charge (30) can be burned ), characterized in that it comprises:

At least one lamination cavity (6) which is arranged in the cylinder head (3) and is connected to the combustion chamber (5) by a lamination duct (7) and which, on the other hand, receives a lamination injector (8) which can directly or indirectly inject into said cavity (6) a pilot charge (9) previously pressurized by compression means (10), said load (9) consisting of a mixture AF fuel oxidant highly flammable by means of a spark;

• ignition means (1 1) which open into the lamination cavity (6) and which can ignite the pilot charge (9);

• A stratification valve (13) which can completely or partially close the lamination duct (7) and which exposes, on the one hand, a cavity-side face (14) subjected to the pressure of the gases prevailing in the lamination cavity ( 6) and on the other hand, a chamber side face (15) subjected to the pressure of the gases in the combustion chamber (1 1), said laminating valve (13) being able to translate with respect to said duct (7) under the effect of the pressure of the gases either towards the lamination cavity (6) when said pressure prevailing therein is lower than the pressure prevailing in the combustion chamber (5), or towards said chamber (5) when the pressure prevailing in the latter is lower than the pressure prevailing in the lamination cavity (6);

At least one cavity-side check stopper (16) which determines the position of the laminating valve (13) closest to the lamination cavity (6);

• At least one chamber-side valve stop (17) which determines the position of the laminating valve (13) closest to the combustion chamber (5).

Valve ignition chamber according to Claim 1, characterized in that the laminating valve (13) completely or partially closes the laminating duct (7) when it is closest to the lamination cavity (6) while it opens said duct (7) on a wider section when it is positioned closer to the combustion chamber (5).

Valve ignition chamber according to Claim 1, characterized in that the cavity-side valve abutment (16) consists of a valve closure seat (18) arranged in the laminating duct (7) or to any of the ends of said duct (7), said seat (18) cooperating with a cavity-side valve seat (19) which the lamination valve (13) has at its periphery and / or at its end.

4. Valve ignition chamber according to Claim 3, characterized in that the valve closing seat (18) and the cavity-side valve seat (19) form a seal when in contact with each other. other, said sealing preventing any gas from passing at said contact when the pressure in the combustion chamber (5) is greater than the pressure in the lamination cavity

(6).

Valve ignition chamber according to Claim 1, characterized in that the chamber-side valve stop (17) consists of a valve-opening seat (20) arranged in the lamination duct (7) or at any one end of said duct (7), said seat (32) cooperating with a chamber-side valve seat (21) which the lamination valve (13) has at its periphery and / or at its end. Valve ignition chamber according to Claim 5, characterized in that the valve opening seat (20) and the chamber-side valve seat (21) form a seal when in contact with one another. other so as to prevent any gas from passing at said contact. Valve ignition chamber according to Claim 1, characterized in that the laminating valve (13) has at its periphery guide means (22) which hold said valve (13) approximately centered in the laminating duct.

(7), and approximately in the same longitudinal orientation as said duct (7) and this, regardless of the axial position of said valve (13) relative to said duct (7).

Valve ignition chamber according to Claim 5, characterized in that when the valve opening seat (20) and the chamber-side valve seat (21) are in contact with one another, the laminating valve (13) forms with the laminating duct (7) a torch ignition pre-chamber (23) which simultaneously communicates with the laminating cavity (6) on the one hand, and with the combustion chamber (5) via at least one gas ejection port

(24).

9. Ignition chamber valve according to claim 8, characterized in that the inner peripheral wall of the ignition prechamber torch (23) is cylindrical while the laminating valve (13) has a circular periphery and is housed at low radial clearance in said prechamber (23).

Valve ignition chamber according to Claim 8, characterized in that the lamination duct (7) protrudes into the combustion chamber (5) in the form of a protruding ejection dome (25) which houses the ignition prechamber torch (23) and which opens the gas ejection port (24).

1 1. Ignition chamber with valve according to claim 10, characterized in that the valve opening seat (20) is arranged in the protruding ejection dome.

(25).

12. Ignition chamber valve according to claim 1, characterized in that when the laminating valve (13) is positioned close to the combustion chamber (5), ie in the vicinity or in contact with the abutment of valve chamber side (17) with which it cooperates, said valve (13) discovers at least one gas ejection port (24) which relates the lamination cavity (6) with the combustion chamber (5).

13. Ignition chamber valve according to claim 1, characterized in that the ignition means (1 1) consist of a spark plug (12) which closes the first end of a perforated connecting tube (26) which crosses all or part of the internal volume of the lamination cavity (6) and whose body is radially traversed by at least one radial slot (27) which connects the inside of said tube (26) with said volume internal, while the second end of said tube (26) receives the lamination duct (7) and the lamination valve (13), and yet that the central electrode (40) and the ground electrode (39) of said candle (12) are housed inside the perforated connecting tube (26).

14. Valve ignition chamber according to claim 1, characterized in that the cavity-side face (14) exposes an aerodynamic dome (29).

Valve ignition chamber according to Claim 1, characterized in that the cavity-side face (14) forms a ground electrode (39) which faces a central electrode (40) which comprises a spark plug ( 12) the latter constituting the ignition means (1 1).

16. Valve ignition chamber according to claims 3 and 5, characterized in that the laminating valve (13) is axially thicker at its periphery which receives the cavity-side valve seat (19) and the side valve seat room (21), only in the center.