ELECTRODE-NAVETTE IGNITION CANDLE

专利摘要:
The shuttle-electrode ignition plug (1) is provided for an internal combustion engine (2) having a combustion chamber (11) in which a main charge (12) diluted with a neutral gas is ignited, said spark plug (1) accommodating a lamination cavity (15) into which a central electrode (6) opens and in which a lamination injector (17) is able to inject under pressure a pilot charge (18) consisting of an oxidant-fuel mixture AF easily flammable, said cavity (15) being connected to the combustion chamber (11) by a lamination duct (16) while a shuttle electrode (20) is intercalated between the central electrode (6) and a mass electrode (7) and can translate into the lamination duct (16).
公开号:FR3060222A1
申请号:FR1662254
申请日:2016-12-09
公开日:2018-06-15
发明作者:Vianney Rabhi
申请人:Vianney Rabhi；
IPC主号:

专利说明:

® FRENCH REPUBLIC
NATIONAL INSTITUTE OF INDUSTRIAL PROPERTY © Publication number: 3,060,222 (to be used only for reproduction orders)
©) National registration number: 16 62 254
COURBEVOIE © Int Cl ⁸ : H 01 T13 / 54 (2017.01), F 02 P 13/00, F 02 B 19/12
A1 PATENT APPLICATION
©) Date of filing: 09.12.16.(© Priority: © Applicant (s): RABHI VIANNEY - FR. @ Inventor (s): RABHI VIANNEY. ©) Date of public availability of the request: 15.06.18 Bulletin 18/24. ©) List of documents cited in the preliminary search report: See the end of this booklet (© References to other related national documents: ® Holder (s): RABHI VIANNEY. ©) Extension request (s): © Agent (s): COLBERT INNOVATION.
(64) SPARK PLUG WITH ELECTRODE-SHUTTLE.
FR 3 060 222 - A1 (6j) The spark plug with shuttle electrode (1) is intended for an internal combustion engine (2) which has a combustion chamber (11) in which a main charge is ignited (12) diluted with a neutral gas, said spark plug (1) accommodating a stratification cavity (15) into which opens a central electrode (6) and into which a stratification injector (17) can inject under pressure a pilot charge (18 ) made of an easily flammable AF-fuel mixture AF, said cavity (15) being connected to the combustion chamber (11) by a stratification duct (16) while a shuttle electrode (20) is interposed between the central electrode (6) and a ground electrode (7) and can translate in the stratification duct (16).
SPARK PLUG WITH ELECTRODE-SHUTTLE
The subject of the present invention is a spark plug with a shuttle electrode which makes it possible to ignite a main charge introduced into the combustion chamber of an internal combustion engine either by means of a spark alone or by means of a pilot charge known per se and ignited by a spark, said spark plug being designed to optimize the efficiency of said pilot charge in lighting said main charge.
The maximum and average efficiency of alternative internal combustion internal combustion engines according to the state of the art is relatively low. In motor vehicles, the maximum efficiency is around thirty-five percent for Otto cycle spark ignition engines, and around forty percent for Diesel cycle engines. As for 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 fuel and which is not transformed into useful work is mainly dissipated in the form of heat in the cooling system and at the exhaust of said engines.
In addition to poor performance, alternative internal combustion engines used in cars produce polluting gases and particles harmful to the environment and human health.
Despite these not very advantageous characteristics, in the absence of other solutions offering a better energy, environmental, functional and economic compromise, internal combustion thermal engines with Otto or Diesel cycles equip almost all of the motor vehicles circulating in the world. .
This situation explains the significant research and development efforts made by engine manufacturers to improve by all means the energy and environmental balance of internal combustion thermal engines. Said efforts are aimed in particular at perfecting the technologies which constitute said engines, and at adding to these latter new functionalities which allow the implementation of new strategies.
Among these strategies is the dilution of the air and fuel load of alternative internal combustion engines either with neutral gas or with fresh oxygen-rich air.
It is to said dilution that the present invention is addressed, which is particularly intended for reciprocating internal combustion internal combustion engines with spark ignition which most often consume either petrol or natural gas.
Diluting the load of spark ignition engines with fresh air or with previously cooled exhaust gases increases the average and / or maximum thermodynamic efficiency of said engines. This results in reduced fuel consumption for the same work produced.
When spark ignition engines operate at partial torque, introducing a diluted charge into their cylinder (s) produces less pumping losses than introducing an undiluted charge. The reduction in said losses results from the fact that the diluted charge is larger with the same energy content. Thus, to introduce the same amount of energy into said cylinder (s), the valve intake intake of said engines usually carried out by means of a throttle valve is less pronounced, and the pressure of the gases which appear at said intake is higher.
In addition, with the same energy introduced into the cylinder or cylinders of spark-ignition engines, diluting the charge increases the mass and the total heat capacity of the latter. Thus, all other things being equal, the combustion of said charge takes place at a lower temperature. In addition to reducing the quantity of nitrogen oxides produced by combustion, said low temperature reduces the heat losses to the walls of the cylinder (s) which result from the transfer by said charge of part of its heat to said walls.
Finally, particularly if the charge is diluted with a neutral gas poor in oxygen or even devoid of oxygen, said charge is less sensitive to uncontrolled self-ignition of the air-fuel mixture. Said auto-ignition is responsible for knocking, an undesirable phenomenon characterized by explosive combustion which deteriorates the performance of spark-ignition engines and which damages the mechanical components which constitute them. The knock desensitization provided by the dilution of the charge allows said engines to either operate at a higher compression ratio, or to operate with an ignition that is triggered at the most favorable time for performance, or both.
In this particular context of diluted air and fuel charges, a distinction is made between spark-ignition engines operating at stoichiometry and said engines operating in excess of air, also known as “lean mixture”.
Only the engines operating at stoichiometry are compatible with a three-way catalyst, a device known in itself which post-treats the pollutants resulting from combustion. Said catalyst is responsible for burning the hydrocarbons which have not been burned in the combustion chamber of the heat 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 the notoriously polluting carbon monoxide to transform it also into carbon dioxide, and reduces the nitrogen oxides to transform them into atmospheric dinitrogen which constitutes approximately seventy-eight percent of the terrestrial atmosphere, which is inherently 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 quantity of oxygen necessary for the combustion of the hydrocarbons contained in said charge.
Excess oxygen makes it impossible to reduce nitrogen oxides by the three-way catalyst. It is therefore not possible to post-treat the nitrogen oxides contained in the exhaust gases from engines operating in excess of air using a three-way catalyst.
This explains why - to meet ever more stringent environmental regulations - engines operating in excess of air now receive a device specially designed to reduce nitrogen oxides such as a nitrogen oxide trap or a catalytic reduction device of nitrogen oxides with urea. Said apparatus is generally placed at the outlet of a two-way oxidation catalyst which will have previously burned unburnt hydrocarbons and which will have completed the oxidation of carbon monoxide, and more and more often, a particle filter.
Since Diesel engines naturally operate 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 which post-processes nitrogen oxides to transform them in dinitrogen.
The problem with these devices is that they are expensive, complex, and their size and maintenance constraints are high to the point that said devices are almost used only on diesel engines which can in practice only operate in excess of 'air.
In the case of spark-ignition engines, engine manufacturers make every effort to make them work at stoichiometry so that they remain compatible with a three-way catalyst which remains simple and inexpensive.
To benefit from the reduction in fuel consumption induced by the dilution of the charge of spark-ignition engines without having to suffer the disadvantages, in particular economic, of a nitrogen oxide trap or a device for selective catalytic reduction of oxides from nitrogen to urea, it is therefore necessary to dilute said charge of said engines not with oxygen-rich air, but with a neutral gas devoid of oxygen.
This latter gas is usually supplied by recycling the exhaust gases from the engine itself, said gases no longer containing oxygen and being available and abundant. This strategy is known by the name of "exhaust gas recirculation" and more precisely by the English acronym "EGR" valid for "Exhaust Gas Recirculation".
Said gases leaving at high temperature at the exhaust of the positive-ignition engine, to prevent them from overheating the charge introduced into said engine, it is necessary to reduce the temperature before mixing them with the fresh gases.
This strategy is known by the Anglo-Saxon name of "Cooled EGR", which specifies that the recirculated exhaust gases are cooled before they are mixed with the fresh gases admitted by said engine. French-speaking engine manufacturers finally use the term "franglais" of "cooled EGR", which is easily understood and easy to use.
EGR gas pre-cooling is required for at least two reasons.
Firstly, the temperature of the gas-EGR / gas-fresh mixture admitted by the positive-ignition engine must remain low so that the volumetric efficiency of said engine remains high when it operates 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. Pre-cooling the EGR gases is made even more essential if the said engine is supercharged by a turbocharger or by any other means.
Secondly, the hotter the gas-EGR / gas-fresh mixture, the more it promotes the appearance of rattling which is unfavorable to the performance of said engine.
The problem is that the charge diluted with cooled EGR is poor in oxygen. This is paradoxical since it is also the aim sought in particular so that the charge remains stoichiometric and resistant to knocking. The result of this oxygen depletion is an initiation of combustion which is more difficult to obtain and a development of combustion slower than when said charge is nondiluted with cooled EGR.
In a spark-ignition engine, combustion is initiated by creating a high-temperature electric arc between two electrodes spaced a few tenths of a millimeter apart.
When the air-fuel charge is highly diluted with cooled EGR, the electric arc passes through a mixture that is generally poor in oxygen and fuel. The risk of a misfire increases if by chance, the space of a few tenths of a millimeter which separates the cathode from the anode of the spark plug does not contain a sufficiently gas-EGR / gas-fresh mixture 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 starts as desired, the fuel energy in the charge begins to release as heat and the flame begins to develop. 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 which 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 positive-ignition engine.
The main problem with cooled EGR is that it makes initialization of combustion difficult, then considerably slows the development of the latter both because of the overall reduction in its temperature, and because of the heterogeneities of richness in oxidizer and / or fuel found in the volume of the combustion chamber and therefore on the path of the flame.
It has been found experimentally that the more the content of the charge in cooled EGR increases, the more the engine becomes unstable. After a certain so-called content, misfires occur and the yield - which hitherto has tended to increase with the EGR content of the charge - decreases. Beyond a certain EGR content, the positive-ignition engine stops, the combustion no longer being able to initialize.
It is also noted that the content of the exhaust gases in unburnt hydrocarbons and in carbon monoxide increases in parallel with the content of cooled EGR in the feed. This stems both from pockets of mixture too poor to burn properly encountered by the flame on its route, and from the thickening of the flame jamming boundary layer near the cold internal walls of the combustion chamber of the engine.
Still experimentally, we also note that the greater the ignition power, the more it is possible to increase the EGR content of the charge without too much 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 so as to push back the accessible limits of cooled EGR content by 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 efficiency decreases rapidly with their power. It therefore always takes more electrical power to obtain less and less additional ignition power.
In addition, high electrical power is only of interest if the electrodes of the spark plug are moved away from each other to give the spark more chance of passing through a burnable pocket, or when the 'the duration of the spark is increased, or the spark is repeated. This leads to increasingly higher voltages and electrical powers which complicate the production of electrical insulators for the spark plug while drastically reducing the life of the latter.
The difficulty in igniting the load also stems from the fact that the cooled EGR is all the more advantageous on supercharged spark-ignition engines which we seek by all means to reduce the sensitivity to knocking. However, the higher the boost pressure, the greater the density of the gas-EGR / gas-fresh mixture between the spark plug electrodes when the spark is triggered, and the more voltage it takes to cause said spark.
From this point of view, the cooled EGR is not going in the right direction since with the same energy introduced into the cylinder of the engine, the mass of gas which is between the electrodes increases as does the resistance of said gas to auto-ignition.
It should be noted that patent number FR 2 986 564 belonging to the applicant constitutes a robust response to these problems. The high-pressure spark and stratification ignition device for an internal combustion engine referred to in said patent proposes to inject under high pressure, at the center of the spark plug and shortly before the triggering of the spark, an approximately stoichiometric pilot charge, highly burnable because not diluted with cooled EGR, and potentially slightly rich in fuel.
Once injected by said device, said pilot charge bathing the spark plug electrodes, as soon as an electric arc forms between said electrodes, said charge ignites immediately and releases the energy it contains. Thus, said charge itself constitutes the ignition means per se, the power of which is several hundreds to several thousand times greater than that of the electric arc which allowed it to be ignited. It is practically impossible to obtain such ignition power with electrical means alone.
Experience has shown, moreover, that cooled EGR rates on the order of fifty percent are possible with such a device, compared to only on the order of thirty percent with the single most powerful electrical ignition devices which are.
Note that the approach adopted in patent N ° FR 2 986 564 is found in related forms in patent N ° US 4 319 552 by the inventors Fred N. Sauer and J. Brian Barry, or in patent N ° DE 41 40 962 A1 belonging to the company "Bosch".
In any event, patent No. US6564770 of the company "Orbital" does not fall into this category because, according to this patent, it is a question of ensuring at relatively low pressure the constitution of a main charge as homogeneous as possible , and not to form a pilot charge for the purpose of igniting a main charge highly diluted with EGR.
The problem of the device described by patent No. FR 2 986 564 and in the related patents as they have just been listed does not lie in the initialization of combustion which is very efficient, but in the development of said combustion . In particular, when the burnt fraction of the fuel contained in the main charge reaches approximately 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 l '' of a main charge not diluted with cooled EGR.
As a result, part of the potential energy gain from the cooled EGR is lost due to combustion that develops too slowly.
However, the maximum benefit of cooled EGR would be found if it were possible to operate a spark ignition engine simultaneously with a main charge, the content of cooled EGR of which is on the order of fifty percent. , and with a stability and a total duration of combustion 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 spark plug electrodes and even, being an integral part of said spark plug as proposed by patent No. US 4,319,552.
The first advantage of such a prechamber is that it potentially keeps the pilot charge as close as possible to the spark plug electrodes, which can limit the dispersion of said charge in the main combustion chamber of the spark-ignition engine before switching on. said charge fire.
The second advantage of said prechamber is that once ignited, the pilot charge pressurizes said prechamber which sends torches of hot gases at high speed into the main combustion chamber of the spark-ignition engine via orifices that said prechamber contains.
This ignition 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 towards 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 positive-ignition engine because not only is the trigger more productive in work, but the less sensitivity to knocking which results from a such rapid combustion makes it possible to operate said engine with a significantly higher volumetric ratio.
In any event, patent No. US 4,319,552 or the solution proposed in patent FR 2 986 564 belonging to the applicant or in the related patents mentioned above cannot be compared to the multitude of patents which inject fuel alone into a prechamber or not, and not a mixture consisting of air and fuel.
These patents include, for example, those known under No. GB 2,311,327 A from "Fluid Research Limited", No. US 4,864,989 from "Tice Technology Corp", No. US 4,124,000 from "General Motors", N ° US 4,239,023 of "Ford Motor Company", N ° US 4,892,070 of the inventor Dieter Kuhnert, N ° US 2001/0050069 A1 of the inventors Radu Oprea and Edward Rakosi, or the patent N ° 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 Formula 1 engines.
There is indeed a fundamental difference between the solutions set out in these latter patents which are intended for spark-ignition engines known as “lean mixture” and which have the objective only of enriching the fuel load around the point of ignition on the grounds that the charge as a whole is poor in fuel but rich in oxygen, and the solutions set out in patent FR 2 986 564 and related patents which, in turn, are mainly intended for positive-ignition engines operating with a highly charged diluted with cooled EGR and which aim to constitute a mixture rich in fuel AND oxygen around the ignition point, on the grounds that the charge as a whole is poor in fuel AND oxygen.
At this stage, we have seen that injecting a highly burnable pilot charge consisting of air and fuel to wrap the spark plug electrodes with said charge as proposed in patent No. FR 2 986 564 makes it possible to efficiently ignite a charge. principal strongly diluted with EGR.
It has also been seen that once said main charge is ignited, combustion develops rapidly until about fifty percent of the total amount of fuel contained in said charge has been burned. Beyond the said 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 spark plug electrodes are housed, this latter problem of combustion development beyond fifty percent would be resolved in whole or in part.
Indeed, said prechamber would eject through its orifices torches of hot gas animated by a high speed which would both initiate combustion over a great radial length around the point of ignition, but also, crease the flame front which would favor the development of the flame perpendicular to the said torches.
However, this latter solution is not entirely satisfactory for a large number of reasons, some of which have led to abandoning the ignition devices based on a prechamber, particularly in the context of spark-ignition engines.
Indeed, to be effective, the prechamber must have a dome which is sufficiently protruding so that the holes through which the hot gases are ejected to form torches do not lick the cold internal walls of the engine. By passing at high speed through said holes, said gases heat said dome which - from a certain temperature - behaves like a "hot ball" like the ignition system of the internal combustion engine invented by Stuart Herbert -Akroyd and described in patent CHD4226 of December 4, 1891. Such a hot spot then potentially leads to inadvertent ignitions of the main charge not controlled by spark. The clicking that can follow is likely to damage or even destroy the spark ignition engine.
One solution may consist in intensively cooling said dome to prevent it from forming a hot spot. However, the export of heat which results therefrom is carried out to the detriment on the one hand, of the efficiency of hot gas torches whose temperature and velocity are reduced during their passage through the holes arranged in said dome, and on the other hand, the thermodynamic efficiency of the positive-ignition engine.
In other words, either the dome is too hot or too cold and above all, the ignition of the main load becomes too dependent on the pre-chamber and the pilot load. This dependence is a handicap when the positive-ignition engine requires little or no dilution of its main charge with EGR, which occurs in many cases.
Indeed, the constitution of an air-fuel pilot charge carried at high pressure is not free from an energy point of view. It is necessary to compress air beforehand, which requires a compressor driven by the spark-ignition engine itself, then inject fuel into said air. Another strategy may consist in directly compressing an air-fuel mixture formed beforehand.
It will be noted that because of its non-negligible energy cost, with the same ignition efficiency, the smaller the mass of the pilot charge relative to that of the main charge, the better the final energy balance of the spark-ignition engine when 'it operates with a high EGR rate. Everything must therefore be done to give the pilot charge a specific efficiency in lighting the main charge as large as possible, relative to the mass of said pilot charge.
In other words, at the same ignition efficiency, the pilot charge must lead to the compression of the smallest amount of air-fuel mixture possible, under the lowest possible pressure.
However, the energy expenditure linked to the compression of the pilot load is not always justified, especially when the main load is little or not diluted with EGR. However, at partial loads - which characterize the operation of an automobile engine for most of its operating time - pumping losses can be reduced by flexible control of the intake valves.
At partial loads, this strategy known by the Anglo-Saxon term of “variable actuation valve” advantageously replaces the EGR and leads to positive ignition engine yields similar to those allowed by said EGR without having to resort to a load expensive driver.
High loads under heavy turbocharging can also be another case where pilot load is not required.
Indeed, the EGR increases the required boost pressure at the same energy introduced into the cylinder (s) of the spark ignition engine. At very heavy loads and while the load of said engine is diluted with EGR, to obtain the desired power for the spark-ignition engine, the supercharger must provide more work than if the load was not diluted. Above a certain EGR rate, the turbine placed at the engine exhaust no longer has enough power to drive said compressor. The accessible EGR rate is limited to the point that the pilot charge is no longer necessary to guarantee the initialization and development of combustion.
In short, the ideal situation would consist in lighting the main charge by means of a conventional spark plug when said charge is little or not diluted with EGR, and by means of an ignition device by pilot charge if possible. with prechamber when said charge is highly diluted with EGR.
A second candle could possibly overcome this need. However, it is practically impossible to accommodate said second spark plug in the cylinder head of a modern automobile engine equipped with four valves per cylinder and an injector which opens directly into the combustion chamber.
So, if we wanted to benefit from both the advantages of the first part, a prechamber as described for example in US Pat. No. 4,319,552 when using pilot charge injection according to the principles set out in the patent FR 2 986 564 and secondly, from a conventional ignition with a conventional spark plug, it would be necessary to be able to retract said prechamber when the conventional spark plug operates and vice versa.
In addition, it would be necessary that when the prechamber is used, the latter cannot behave like a “hot ball” ignition device as previously mentioned or at least, that the initialization of the combustion of the main charge is well triggered at the chosen time, and not suffered at an uncontrolled time.
This involves cooling the hot parts of the prechamber which can trigger self-ignition without reducing the effectiveness of said prechamber in diffusing hot gas torches in the three-dimensional space of the engine combustion chamber which contains the main charge.
However, since modern supercharged engines almost systematically receive a direct injection of petrol, the adoption of a pre-chamber in which the electrodes of the spark plug are housed for the purpose of igniting a pilot charge is almost impossible. if you want to use the same means to be able to switch on the main load without using the pilot load.
Indeed, strongly diluting the charge with cooled EGR is very advantageous on this type of engine. However, the electrodes of the spark plug of turbocharged direct injection engines must be protruding so that the highly burnable fuel mixture formed by the fuel injector bathes said electrodes. However, if said electrodes are inside a prechamber provided with holes, this condition is not fulfilled and the initialization of combustion can no longer be guaranteed. To circumvent this problem, it would be necessary to systematically resort to pilot charge ignition, the energy cost of which is not marginal.
The difficulty of reaching the spark plug electrodes with the fuel mixture if said electrodes are housed in a prechamber is particularly addressed, for example, in patent No. EP 1 464 804 A1 of the company "Peugeot Citroën Automobiles" in which a claim is made. significant direct injection pressure making it possible to promote the penetration of a part of the airessence mixture inside the prechamber via the orifices passing through the wall of said prechamber.
Moreover, this last patent inherits the principles of patent N ° EP 1 411 221 A2 from the same applicant in which is implicitly addressed the effect of “hot ball” potentially produced by the prechamber and feared by engine manufacturers for its triggering effect of rattling.
Indeed, in claim No. 10 of said patent, it is proposed to produce the wall of the prechamber with an alloy having a thermal conductivity at 20 ° C of at least 10W / K / m and preferably at least 30W / K / m. It is understood that this characteristic is sought so that the wall of the prechamber cools down as quickly as possible to avoid the "hot ball" effect.
In claim No. 13 of the same patent, it is also discovered that the walls and the orifices of the prechamber can be coated with a refractory material, this being indicative of the need to keep a material also sufficiently hot so as not to reduce too much the temperature of the hot gas torches, and to avoid excessive export of heat to the cold parts of the heat engine.
However, such a refractory material would not fail to promote the "hot ball" effect which is, moreover, unacceptable.
It is easy to understand, moreover, that the potential problems set out in patents No. EP 1 464 804 A1 and EP 1 411 221 A2 which have just been cited are found in a different form in numerous patents which describe spark plugs. in which a prechamber is fitted. Among these patents, note that known under the number DE 0 675 272 A1 and its variant WO 03/071644 A1, and those published under the numbers EP 1 143 126A2 or EP 1 701 419 A1.
It will be noted that the idea of producing candles with an integrated pre-chamber is old, as attested by patent N ° US 2,047,575 of July 14, 1936.
Besides, the candles exhibited in these patents have a "passive" pre-chamber which consists of a simple cap provided with orifices. This type of prechamber is mainly used in engines operating at stabilized speed. Indeed, the section of the orifices of said prechamber are provided so that a sufficient differential pressure is obtained at the time of ignition of the fraction of charge contained in the prechamber so that the hot gas torches reach an ejection speed sufficient through said orifices.
The problem is that if the prechamber is emptied via said orifices, it also fills via the same orifices. Consequently, the use of such spark plugs results from a precise balance between the section of the holes and the speed of rotation of the engine. This helps explain why this type of spark plug is not used in cars where the speed of the spark-ignition engine is constantly changing.
In addition to the problems posed by the high temperature of the prechamber and by its filling and emptying, it will be noted that in the particular context of the injection of a pilot charge consisting of a mixture of air and fuel as proposed in Patent No. FR 2 986 564 also poses the problem of the dispersion of said pilot charge in the main charge, before firing said pilot charge. Any such dispersion reduces the specific efficiency of the pilot charge in igniting the main charge. This can only be compensated for by increasing the mass of said pilot charge, which is to the detriment of the final energy efficiency of the spark-ignition engine.
The problem stems from the fact that the injector which introduces the pilot charge into the main charge needs time to inject said pilot charge under a pressure necessarily greater than that of the main charge.
It will also be noted that the injection pressure of the pilot charge remains approximately constant, however that the pressure of the main charge increases under the effect of its compression following the ascent of the piston of the spark-ignition engine towards its Top Dead Center. . The start of injection of the pilot charge therefore takes place under a higher differential pressure than the end of said injection. It follows from this that the speed of ejection of the gases constituting the pilot charge is greater at the start of injection than at the end of injection.
Unless a large volume prechamber is available, which is not possible, part of the pilot charge will inexorably exit through the orifices of the prechamber and mix with the main charge which has a high EGR content. The mixture between pilot charge and main charge will be particularly pronounced at the start of injection. The flammability of the mixture thus formed of air, fuel and EGR will therefore necessarily be heterogeneous in the volume of the prechamber and outside the prechamber. The efficiency of the pilot charge to ignite as quickly as possible will be reduced, as will the effectiveness of hot gas torches to ignite the main charge. This drop in efficiency can only be compensated by an increase in the air and fuel mass of the pilot charge, to the detriment of the overall energy efficiency of the spark-ignition engine.
Ideally, it should therefore be avoided by all means to disperse the pilot charge in the main charge before the ignition of said pilot charge.
Always ideally and as we have seen previously, the pilot air-fuel charge should be injected into a prechamber only when the spark-ignition engine operates at high EGR rate while when said engine operates only at low EGR or even nil, a conventional spark plug would be used to light the main load.
This would always be in line with the objective - the engine operating at a high EGR rate cooled - to limit the mass of the pilot load as much as possible to minimize the energy cost of compression, and to increase efficiency as much as possible of said pilot load to switch on the main load.
When only a conventional spark plug is used to light the main charge it would - ideally still - be necessary for the pre-chamber to disappear so that it cannot in any way behave like a "hot ball".
Ultimately, it would be very advantageous to confer on the device described by patent No. FR 2 986 564 which has proved effective to initialize combustion under very high EGR levels cooled and to develop said combustion until a approximately fifty percent fraction of the fuel in the main charge is burned, the ability to very rapidly develop said combustion until a fraction of at least ninety or one hundred percent of said fuel is burned.
This could be achieved by means of a prechamber as suggested by patent No. US 4,319,552, but on the sole condition of circumventing the usual unacceptable defects of said prechamber, and of significantly improving its efficiency.
All of these objectives are addressed by the spark plug spark plug according to the invention which - according to a particular embodiment - allows:
• To benefit with a single spark plug from the advantages of a prechamber into which a pilot charge is injected and then ignited to ignite a main charge by means of hot gas torches, and the advantages of non-protruding electrodes enclosed in a prechamber, compatible with direct gasoline injection, and enabling the main charge to be ignited directly by means of an electric arc formed between said electrodes;
• Avoid that the prechamber does not generate any hot spot likely to cause untimely self-ignition of the main charge;
• To minimize the mass of the pilot charge necessary not only to initiate the combustion of main charges highly diluted with EGR, but also to ensure rapid development of said combustion until all of said main charges are burned.
• For the latter purpose, to avoid the dispersion of the pilot charge in the main charge during the injection of said pilot charge into said main charge.
To achieve these objectives, the spark plug with shuttle electrode according to the invention provides:
• Retract the prechamber when it is unnecessary, said prechamber then being replaced by protruding electrodes;
• The prechamber being retracted, actively cooling the surface of said prechamber exposed to hot gases, between two combustion cycles;
• Keep the prechamber closed for most of the pilot charge injection time, which takes place in an enclosed space in which the gases from the pilot charge cannot mix with the gases from the main charge.
It will be noted that the spark plug with shuttle electrode according to the invention does not imply significantly increasing the electric voltage at the terminals of said spark plug to cause the ignition spark, said voltage remaining in the vicinity of the voltages usually retained. for ordinary spark plugs.
Said spark plug with shuttle electrode is expected to be inexpensive to mass produce to remain compatible with the economic constraints of most of the applications for which it is intended, including automobiles. In addition, the life of said spark plug is assumed to be similar to that of a conventional spark plug.
It is understood that the spark plug with shuttle electrode according to the invention can be applied to any spark ignition engine with internal combustion whatever the type, whatever the gaseous, liquid or solid fuel that it consumes, and whether its main charge is diluted with EGR cooled or not, with a neutral gas of any kind, or with a gas rich in oxygen or any other oxidizer.
It is also understood that the pilot charge received by the prechamber of the spark plug with shuttle electrode according to the invention may contain a fuel and / or an oxidizer different from the fuel and / or oxidizer which constitutes the main charge of the engine to controlled ignition.
The spark plug with shuttle electrode according to the present invention is intended for an internal combustion engine which comprises at least one cylinder in which can translate a piston to form - with a cylinder head - a combustion chamber in which can be put fire a main charge, the latter being made up of an oxidizer-fuel mixture on the one hand, and being more or less diluted with oxygen-rich air or with a neutral gas on the other hand, said internal combustion engine also comprising a intake duct and an exhaust duct opening into said chamber.
The spark plug with a shuttle electrode according to the present invention comprises at least electrodes and a ceramic insulator housed in a metal base which has a base thread, and at least one central electrode, and at least one ground electrode, said spark plug also receiving a stratification cavity connected to the combustion chamber which the internal combustion engine comprises by a stratification duct while a stratification injector can directly or indirectly inject into said cavity a pilot charge previously pressurized, said charge consisting of an oxidizer-fuel mixture AF easily inflammable by means of a spark, said spark plug with shuttle electrode comprising according to the invention:
• At least one central electrode which opens into the stratification cavity;
• At least one shuttle electrode which is wholly or partly made of an electrically conductive material and which is partially or entirely housed with little play in the laminating duct, said shuttle electrode being inserted between the central electrode and a ground electrode and having, on the first hand, a chamber side end which faces the ground electrode and which is exposed to the pressure prevailing in the combustion chamber and secondly, a cavity side end which faces the central electrode and which is exposed to the pressure prevailing in the stratification cavity, said electroduct being able to translate in said duct under the effect of the gas pressure either towards the stratification cavity when the pressure prevailing in the latter is less than the pressure prevailing in the combustion chamber, ie in the direction of the combustion chamber when the pressure r prevailing in the latter is less than the pressure prevailing in the stratification cavity;
• At least one shuttle electrode stop on the cavity side which determines the position of the shuttle electrode closest to the stratification cavity;
• At least one shuttle electrode stop on the chamber side which determines the position of the shuttle electrode closest to the combustion chamber.
The shuttle electrode spark plug according to the present invention comprises a shuttle electrode which closes all or part of the laminating duct when it is closest to the laminating cavity while it opens said duct on a more large section when positioned closest to the combustion chamber.
The spark plug with shuttle electrode according to the present invention comprises all or part of the laminating duct which comprises an insulating sleeve made of an electrically insulating and / or thermally insulating and / or refractory material, which is integral with said duct, and which is inserted radially and / or axially between the shuttle electrode and said conduit, said shuttle electrode being able to translate inside said sleeve.
The shuttle electrode spark plug according to the present invention comprises an insulating sleeve which has at least one longitudinal gas passage channel which allows the gases to pass from the stratification cavity to the combustion chamber or vice versa, said channel being able to be arranged inside and / or on the internal or external surface of said sleeve.
The shuttle electrode spark plug according to the present invention comprises a shuttle electrode which consists of an insulating shuttle body made of an electrically insulating material, said body being traversed right through its length by a conductive core to which it is integral, said core being made of an electrically conductive material, a first end of said core facing the ground electrode while a second end of said core faces the electrode central.
The shuttle electrode spark plug according to the present invention comprises a cavity-side shuttle electrode stop which consists of a shuttle electrode shut-off seat arranged in the stratification duct or in any one ends of said conduit, said seat cooperating with a shuttle electrode closure flange that the shuttle electrode has at its periphery and / or at its end.
The shuttle electrode spark plug according to the present invention comprises a shuttle electrode shut-off seat and an electrowash shutter collar which constitute a seal when they are in contact with each other, said seal preventing any gas from passing through said contact when the pressure in the combustion chamber is higher than the pressure in the stratification cavity.
The shuttle electrode spark plug according to the present invention comprises a chamber side shuttle electrode stop which consists of a shuttle electrode opening seat arranged in the laminating duct or in any one ends of said conduit, or in the metal base, said seat cooperating with a shuttle electrode opening flange that has the shuttle electrode around its periphery and / or at its end.
The shuttle electrode spark plug according to the present invention comprises a shuttle electrode opening seat and a electrode opening collar which constitute a seal when they are in contact with each other. so as to prevent any gas from passing through said contact.
The shuttle electrode spark plug according to the present invention comprises a shuttle electrode which has at its periphery guide means which maintain said shuttle electrode approximately centered in the laminating duct, and approximately in the same longitudinal orientation as said conduit and this, whatever the axial position of said shuttle electrode with respect to said conduit.
The spark plug electrode with shuttle according to the present invention comprises a shuttle electrode which has at least one longitudinal gas passage channel which allows gases to pass from the stratification cavity to the combustion chamber or vice versa, said channel can be arranged inside and / or on the surface of said shuttle electrode and can be produced either, over the entire length of said shuttle electrode, however the two ends of said channel open respectively at the level from the end on the chamber side and at the end on the cavity side, that is, over only a portion of said length while at least one of the two said ends of said channel opens radially from the external surface of the shuttle electrode .
The shuttle electrode spark plug according to the present invention comprises a shuttle electrode shutter collar and a shuttle electrode opening collar which commonly form a single shutter-opening collar which defines with the stratification duct - when said shutter-opening collar is in contact with the electroplating opening seat - an ignition pre-chamber by torch which communicates simultaneously with the stratification cavity on the one hand, and with the chamber combustion via at least one gas ejection orifice on the other hand.
The shuttle electrode spark plug according to the present invention comprises a torch ignition prechamber which is arranged inside the insulating sleeve.
The shuttle electrode spark plug according to the present invention comprises an insulating sleeve which protrudes from the metal base to present a protruding ejection dome from which opens the gas ejection orifice.
The shuttle electrode spark plug according to the present invention comprises a protruding ejection dome which is an insert on the insulating sleeve.
The shuttle electrode spark plug according to the present invention comprises a shuttle electrode opening seat which is arranged in the protruding ejection dome.
The shuttle electrode spark plug according to the present invention comprises an internal peripheral wall of the torch ignition prechamber which is cylindrical while the shutter-opening flange is housed with low radial clearance in said prechamber.
The spark plug with a shuttle electrode according to the present invention provides that when the shuttle electrode is positioned close to the combustion chamber, that is to say either in the vicinity of or in contact with the shuttle electrode stopper on the chamber side. with which it cooperates, the shuttle electrode shutter flange discovers at least one gas ejection orifice which brings the stratification cavity into contact with the combustion chamber.
The shuttle electrode spark plug according to the present invention comprises a stratification injector which can directly, or indirectly via an injector outlet duct, inject the pilot charge into the stratification cavity by means of a chamber pilot charge injection ring which is arranged either in a threaded spark plug well into which the metal base is screwed by means of the base thread, or on the outer periphery of said metal base, or, both in said well and on said periphery of said base, said annular chamber communicating with the stratification cavity via at least one gas injection channel arranged approximately radially in the metal base.
The shuttle electrode spark plug according to the present invention comprises a stratification cavity which is arranged inside the ceramic insulation.
The description which follows with reference to the appended drawings and given by way of nonlimiting examples will make it possible to better understand the invention, the characteristics which it presents, and the advantages which it is capable of providing:
Figure 1 is a schematic sectional view of the spark plug spark plug 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 spark plug spark plug according to the invention, the shuttle electrode is made of a single piece of electrically conductive material which can translate in an insulating sleeve that includes the conduit of stratification, a seat for closing the electrodavette forming the stop of electrode-shuttle on the cavity side while a seat of opening of electrode-shuttle forms the stop of electrode-shuttle on the chamber side, the two said stops cooperating with a shutter-opening collar presented by the shuttle electrode.
Figures 3 to 8 are partial close-up views in schematic section of the spark plug with a shuttle electrode 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 spark plug.
Figure 9 is a three-dimensional view of the spark plug with a shuttle electrode according to the invention and according to the alternative embodiment shown in Figure 2.
FIG. 10 is a three-dimensional view in broken longitudinal section of the spark plug with a shuttle electrode according to the invention and according to the alternative embodiment shown in FIG. 2.
Figure 11 is an exploded three-dimensional view of the spark plug spark plug according to the invention and according to the embodiment shown in Figure 2.
Figure 12 is a schematic sectional view of the spark plug spark plug according to the invention, the shuttle electrode consists of an insulating shuttle body traversed right through in the direction of its length by a conductive core which it is integral with, the cavity electrode stop abutment consisting of a shuttle electrode shutter seat arranged at the end of the laminating duct, said seat cooperating with a shutter collar shuttle electrode that has the shuttle electrode at its end.
Figures 13 to 18 are partial close-up views in schematic section of the spark plug with a shuttle electrode according to the invention and according to the particular configuration shown in Figure 12, said close-up views illustrating various phases of operation of said spark plug.
FIG. 19 is a three-dimensional view of the spark plug with a shuttle electrode according to the invention and according to the alternative embodiment shown in FIG. 12.
FIG. 20 is a three-dimensional view in broken longitudinal section of the spark plug with a shuttle electrode according to the invention and according to the alternative embodiment shown in FIG. 12.
Figure 21 is an exploded three-dimensional view of the spark plug spark plug according to the invention and according to the alternative embodiment shown in Figure 12.
DESCRIPTION OF THE INVENTION:
FIGS. 1 to 21 show the spark plug electrode 1, various details of its components, its variants, and its accessories.
As illustrated in FIG. 1, the spark plug with a shuttle electrode 1 is provided for an internal combustion engine 2 which comprises at least one cylinder 8 in which a piston 9 can translate to form - with a cylinder head 10 - a chamber combustion 11 in which a main charge 12 can be ignited, the latter consisting of an oxidant-fuel mixture on the one hand, and being more or less diluted with oxygen-rich air or with a neutral gas on the other go.
The internal combustion engine 2 for which the spark plug spark plug 1 is provided further comprises an intake duct 13 and an exhaust duct 14 opening into the combustion chamber 11 while said spark plug 1 comprises an insulator in ceramic 3 housed in a metal base 4 which has a base thread 5.
The shuttle electrode spark plug 1 also comprises at least one central electrode 6 and at least one ground electrode 7 while it also receives a stratification cavity 15 connected to the combustion chamber 11 by a stratification duct 16 while a stratification injector 17 can directly or indirectly inject into said cavity 15 a pilot charge 18 previously pressurized by a stratification compressor 19, said charge 18 consisting of an oxidizer-fuel mixture AF easily flammable by means of 'a spark.
Figures 1 to 21 show that the shuttle electrode spark plug 1 is distinguished from the prior art in that the central electrode 6 opens into the stratification cavity 15.
In addition, FIGS. 1 to 21 illustrate the fact that the spark-plug spark plug 1 comprises a shuttle electrode 20 which is wholly or partly made of an electrically conductive material and which is partially or entirely housed in low clearance in the stratification duct 16.
It will be noted in FIGS. 1 to 21 that the shuttle electrode 20 is inserted between the central electrode 6 and the ground electrode 7 and has, firstly, an end on the chamber side 21 which faces the ground electrode 7 and which is exposed to the pressure prevailing in the combustion chamber 11 and secondly, one end on the cavity side 22 which faces the central electrode 6 and which is exposed to the pressure prevailing in the stratification cavity 15.
It will be noted that according to the spark plug with shuttle electrode 1 according to the invention, the shuttle electrode 20 can translate in the stratification duct 16 under the effect of the gas pressure either in the direction of the stratification cavity 15 when the pressure prevailing in the latter is lower than the pressure prevailing in the combustion chamber 11, ie in the direction of the combustion chamber 11 when the pressure prevailing in the latter is lower than the pressure prevailing in the stratification cavity 15.
It can be noted that the shuttle electrode 20 can also move in the stratification duct 16 under the effect of gravity or an acceleration, which cannot be interpreted as any advantage or a desired mode of operation.
The shuttle electrode spark plug 1 according to the invention further comprises at least one shuttle electrode stop on the cavity side 23 which determines the position of the shuttle electrode 20 closest to the stratification cavity 15.
Finally, said spark plug 1 according to the invention comprises at least one chamber side electroduct stop 24 which determines the position of the shuttle electrode 20 closest to the combustion chamber 11.
It will be noted that according to a particular embodiment of the spark plug with shuttle electrode 1 according to the invention, the shuttle electrode stop on the cavity side 23 and / or the shuttle electrode stop on the chamber side 24 can be consisting respectively of the central electrode 6 and / or the ground electrode 7.
As a variant, the shuttle electrode 20 may include means for indexing in rotation along its longitudinal axis which prevent it from turning along said axis without preventing it from translating in the stratification duct 16.
It will be noted that advantageously, the shuttle electrode 20 and / or the laminating duct 16 in which it translates can be coated with an anti-friction material known per se and / or non-stick and / or refractory.
In addition, the shuttle electrode 20 can be hollow or have lightening means while all types of electrodes known to those skilled in the art can be applied to the central electrode 6, to the ground electrode 7, at the end on the chamber side 21 or at the end on the cavity side 22.
According to a particular embodiment of the spark plug with shuttle electrode 1 according to the invention particularly visible in FIGS. 2 to 21, the shuttle electrode 20 can completely or partially block the stratification duct 16 when it is as close as possible to the stratification cavity 15 while it can open said duct 16 over a wider section when it is positioned as close as possible to the combustion chamber 11.
As illustrated in FIGS. 2 to 11, all or part of the laminating duct 16 may comprise an insulating sleeve 25 made of an electrically insulating and / or thermally insulating and / or refractory material, which is integral with said duct 16, and which is inserted radially and / or axially between the shuttle electrode 20 and said conduit 16, said shuttle electrode 20 being able to translate inside said sleeve 25.
It is noted that according to a particular embodiment of the spark plug with shuttle electrode 1 according to the invention, the insulating sleeve 25 may be integral with the ceramic insulator 3 and be arranged in the same piece of material as that latest.
As a variant, an air space can be left between at least part of the insulating sleeve 25 and the laminating duct 16 so as to limit the heat exchanges between said sleeve 25 and said duct 16.
FIGS. 3 to 8 and FIG. 11 show that, as an alternative embodiment of the spark plug with a shuttle electrode 1 according to the invention, the insulating sleeve 25 can comprise at least one longitudinal channel for the passage of gases 35 which allows gases to pass from the stratification cavity 15 to the combustion chamber 11 or vice versa, said channel 35 being able to be arranged inside and / or on the internal or external surface of said sleeve 25.
FIGS. 12 to 21 show in particular that the shuttle electrode 20 can consist of an insulating shuttle body 26 itself made of an electrically insulating material, said body 26 being traversed right through in the direction of its length by a conductive core 27 of which it is integral, said core 27 being made of an electrically conductive material, a first end 28 of said core 27 facing the ground electrode 7 while a second end 29 of said core 27 faces the central electrode 6.
FIGS. 3 to 8, FIG. 11, FIGS. 13 to 18 and FIGS. 20 and 21 allow it to be clearly seen that the shuttle electrode stopper on the cavity side 23 can consist of an electrode closing seat. shuttle 30 arranged in the stratification duct 16 or at any one of the ends of said duct 16, said seat 30 cooperating with a shuttle electrode closure flange 31 which has the shuttle electrode 20 around its periphery and / or at its end.
It is noted that if the stratification duct 16 hosts an insulating sleeve 25, the shutter seat for the shuttle electrode 30 can be arranged in said sleeve 25 or at any one of the ends of said sleeve 25.
It should also be noted that the shuttle electrode closure flange 31 can be made of a thermally insulating and / or refractory material so as to be attached to the shuttle electrode 20 made of electrically conductive material.
As a particular embodiment of the spark plug with shuttle electrode 1 according to the invention, the shuttle electrode shutter seat 30 and the shuttle electrode shutter collar 31 can constitute a seal when they are in contact with each other, said seal preventing any gas from passing through said contact when the pressure prevailing in the combustion chamber 11 is higher than the pressure prevailing in the stratification cavity 15.
FIGS. 2 to 8 clearly show that the shuttle electrode stopper on the chamber side 24 may consist of a shuttle electrode opening seat 32 arranged in the laminating duct 16 or at any one of the ends of said conduit 16, or in the metal base 4, said seat 32 cooperating with a shuttle electrode opening flange 33 which has the shuttle electrode 20 at its periphery and / or at its end.
It is noted that if the stratification duct 16 hosts an insulating sleeve 25, the shuttle electrode opening seat 32 can be arranged in said sleeve 25 or at any one of the ends of said sleeve 25.
It should also be noted that the shuttle electrode opening collar 33 can be made of a thermally insulating and / or refractory material and be attached to the shuttle electrode 20, the latter being made of an electrically conductive material.
It will also be noted that the shuttle electrode opening seat 32 and the shuttle electrode opening flange 33 can constitute a seal when they are in contact with each other so as to prevent any gas from go to the level of said contact.
FIG. 21 clearly makes it possible to observe that the shuttle electrode 20 may comprise, at its periphery, guide means 34 which hold said shuttle electrode 20 approximately centered in the stratification duct 16, and approximately in the same longitudinal orientation as said duct 16 and this, whatever the axial position of said shuttle electrode 20 relative to said conduit 16.
Figures 2 to 21 excluding Figures 9 and 19 show that the shuttle electrode 20 may comprise at least one longitudinal gas passage channel 35 which allows the gases to pass from the stratification cavity 15 to the combustion 11 or vice versa, said channel 35 can be arranged inside and / or on the surface of said shuttle electrode 20 and can be produced either, over the entire length of said shuttle electrode 20, however that the two ends of said channel 35 open respectively at the end of the chamber side 21 and at the end of the cavity side 22, that is, over only a portion of said length while at least one of the two said ends of said channel channel 35 opens radially from the external surface of the shuttle electrode 20.
As shown in FIGS. 2 to 8 and FIGS. 10 and 11, the shuttle electrode shutter collar 31 and the shuttle electrode opening collar 33 can commonly form a single shutter collar- opening 36 which defines with the stratification duct 16 - when said shutter-opening collar 36 is in contact with the shuttle electrode opening seat 32 - an ignition pre-chamber by torch 37.
It will be noted that in this case, the torch ignition prechamber 37 communicates simultaneously with the stratification cavity 15 on the one hand, and with the combustion chamber 11 via at least one orifice for ejecting the gas 38 on the other hand which can for example be arranged approximately radially, in the metal base 4 or in the insulating sleeve 25.
It will be noted that the gas ejection orifice 38 can be more or less oriented towards the combustion chamber 11 and come out more or less tangentially to the circumference of the metal base 4. In addition, the geometry of the ejection orifice gases 38 may vary depending on whether the gas jet leaving said orifice 38 is provided rather directive, or rather diffuse.
By way of example, the gas ejection orifice 38 can be cylindrical, conical, or even form a convergent or a divergent. In addition, the opening shutter collar 36 can be made of a thermally insulating and / or refractory material to be attached to the shuttle electrode 20 made of electrically conductive material.
Figures 3 to 8 and Figures 10 and 11 show that the torch ignition prechamber 37 can be arranged inside the insulating sleeve 25.
In this case, the insulating sleeve 25 can protrude from the metal base 4 to present a protruding ejection dome 47 from which opens the gas ejection orifice 38, said dome 47 can for example be held in position in said base 4 by tabs or by a crimping collar.
Moreover and as illustrated in FIGS. 2 to 11, the protruding ejection dome 47 can be an insert on the insulating sleeve 25 which also consists of an electrically insulating and / or thermally insulating and / or refractory material .
This particular configuration makes it possible in particular to assemble the spark plug with shuttle electrode 1 according to the invention and particularly, to install the shutter-opening collar 36 constituting the shuttle electrode 20 in the ignition prechamber. by torch 37.
FIGS. 3 to 8 show that the shuttle electrode opening seat 32 can be arranged in the protruding ejection dome 47.
As made particularly visible in FIGS. 10 and 11, the internal peripheral wall of the torch ignition prechamber 37 can be cylindrical while the shutter-opening collar 36 can be housed in low radial clearance in said prechamber 37 so leaving a slight radial clearance between said flange 36 and said wall regardless of the position of the shuttle electrode 20 relative to the stratification duct 16, said slight radial clearance constituting a restricted passage which slows down the passage of gases between the stratification cavity 15 and the combustion chamber 11.
It can also be seen in FIGS. 13, 16, 17 and 18 that when the shuttle electrode 20 is positioned close to the combustion chamber 11, that is to say either in the vicinity of or in contact with the shuttle electrode stop chamber side 24 with which it cooperates, the shuttle electrode closure flange 31 can discover at least one gas ejection orifice 38 which relates the stratification cavity 15 to the combustion chamber 11, said orifice 38 can for example be arranged approximately radially in the metal base 4 and be more or less oriented towards the combustion chamber 11 and exit more or less tangentially to the circumference of the metal base 4.
In addition, the geometry of the gas ejection orifice 38 can vary depending on whether the gas jet leaving said orifice 38 is intended to be rather directive, or rather diffuse. By way of example, the gas ejection orifice 38 can be cylindrical, conical, or even form a convergent or a divergent.
According to a particular variant of the spark plug with a shuttle electrode 1 according to the invention particularly shown in FIGS. 2 and 12, the stratification injector 17 can directly, or indirectly via an injector outlet duct 42, inject the pilot charge 18 in the stratification cavity 15 via an annular pilot charge injection chamber 39.
In this case, the annular pilot charge injection chamber 39 is arranged either in a threaded spark plug well 40 into which the metal base 4 is screwed by means of the base thread 5, or on the outer periphery of said metal base 4, or, both in said well 40 and on said periphery of said base 4, said annular chamber 39 communicating with the stratification cavity 15 via at least one gas injection channel 41 arranged approximately radially in the metal base 4 or possibly tangentially to the latter.
It will be noted that, as another variant of the spark plug with shuttle electrode 1 according to the invention, the stratification cavity 15 is arranged inside the ceramic insulator 3. Alternatively, said cavity 15 can be coated with a thermally insulating and / or refractory material.
It will be noted that the main innovative components of the spark plug with shuttle electrode 1 according to the invention such as the shuttle electrode 20, the shuttle electrode stopper on the cavity side 23 or the shuttle electrode stopper on the side chamber 24, can be housed in a base attached to the cylinder head 10 into which the metal base of a conventional spark plug screwless of a ground electrode facing its central electrode is screwed.
FUNCTIONING OF THE INVENTION:
The operation of the spark plug electrode 1 according to the invention is easily understood from the view of FIGS. 1 to 21.
FIG. 1 illustrates that the spark plug with a shuttle electrode 1 is here mounted on an internal combustion engine 2, its metal base 4 being screwed into the cylinder head 10 of said engine 2.
To detail said operation, we will retain here the example of embodiment of the spark plug with shuttle electrode 1 according to the invention as illustrated in FIGS. 2 to 11 in which it can be seen that the shuttle electrode 20 is made of a single piece of electrically conductive material which in this case is a metal. According to this example, the shuttle electrode 20 can translate into an insulating sleeve 25 which comprises the stratification duct 16, which is inserted radially between the shuttle electrode 20 and the stratification duct 16, and which consists of an electrically and thermally insulating material such as ceramic or equivalent.
It can be noted that the insulating sleeve 25 has three longitudinal gas passage channels 35 of large cross section which allow the gases to pass from the stratification cavity 15 to the combustion chamber 11 or vice versa. Said channels 35 are arranged inside said sleeve 25.
It is noted according to this non-limiting example of embodiment of the spark plug with shuttle electrode 1 according to the invention that the shuttle electrode stop on the cavity side 23 consists of a shutter seat for the shuttle electrode 30 arranged at the end of the insulating sleeve 25, said seat 30 cooperating with a shuttle electrode closure flange 31 which has the shuttle electrode 20 at its periphery.
It is understood that the shuttle electrode closure seat 30 and the shuttle electrode closure collar 31 constitute a seal when they are in contact with each other so as to prevent any gas from passing to the level of said contact when the pressure prevailing in the combustion chamber 11 is higher than that prevailing in the stratification cavity 15.
Still according to this exemplary embodiment, it is also noted that the shuttle electrode abutment on the chamber side 24 consists of a shuttle electrode opening seat 32 also arranged in the insulating sleeve 25, said seat 32 cooperating with a shuttle electrode opening collar 33 presented by the shuttle electrode 20 around its periphery and / or at its end.
Note that the shuttle electrode opening seat 32 and the shuttle electrode opening flange 33 constitute a seal when they are in contact with each other so as to prevent any gas from passing to the level of said contact.
Note that according to the particular embodiment of the spark plug with shuttle electrode 1 according to the invention taken here to illustrate its operation, the shutter collar for the shuttle electrode 31 and the opening collar electrodenavette 33 are combined to commonly form a single shutter-opening collar 36. This is particularly visible in FIGS. 2 to 8, and in FIGS. 10 and 11.
Note moreover in FIG. 3, in FIGS. 6 to 8, and in FIG. 10, that when the shutter-opening collar 36 is in contact with the electrodenette opening seat 32 with which it cooperates, it defines with the insulating sleeve 25 a torch ignition prechamber 37 which communicates simultaneously with the stratification cavity 15 on the one hand, and with the combustion chamber 11 via eight gas ejection orifices 38 on the other hand .
According to the example taken here, we will consider that the diameter of said orifices 38 is fifteen hundredths of a millimeter.
As illustrated in particular in FIGS. 2 to 11, in order to receive the ignition prechamber by torch 37, the insulating sleeve 25 is extended by a protruding ejection dome 47 inside which said prechamber 37 is arranged. that said dome 47 protrudes from the metal base 4 and that it is from said dome 47 that the gas ejection orifices 38 open.
As can be seen in FIGS. 2 to 11, the protruding ejection dome 47 is an insert on the insulating sleeve 25 which also consists of a thermally insulating and refractory material, while the electrodenette opening seat 32 is actually located in said dome 47.
It will be noted that the internal peripheral wall of the ignition prechamber by torch 37 is cylindrical while the shutter-opening collar 36 is housed with little radial clearance in said prechamber 37 - for example five hundredths of a millimeter - so as to leave a slight radial clearance between said flange 36 and said wall whatever the position of the shuttle electrode 20 relative to the laminating duct
16.
Said small radial clearance forces the majority of the gases transferred from the combustion chamber 11 to the stratification cavity 15 or vice versa to pass via the gas ejection orifices 38 rather than between the internal peripheral wall of the ignition prechamber by torch 37 and the shutter-opening collar 36.
Note that depending on whether the pressure prevailing in the stratification cavity 15 is lower or higher than the pressure prevailing in the combustion chamber 11, the shuttle electrode 20 can be brought to position either on its electrode stopper. shuttle side cavity 23 as illustrated in FIGS. 4 and 5, that is to say on its abutment of shuttle electrode chamber side 24 as illustrated in FIGS. 2 and 3, FIGS. 6 to 8, and FIG. 10.
In this case and as has just been described, the shuttle electrode stopper on the cavity side 23 is none other than the shuttle electrode shutter seat 30 while the shuttle electrode stopper on the chamber side 24 consists of the shuttle electrode opening seat 32.
When the shuttle electrode 20 is in contact with the shuttle electrode stop on the cavity side 23, the space left between its end on the chamber side 21 and the ground electrode 7 is according to this illustrative example of seven tenths of a millimeter while that the space left between its end on the cavity side 22 and the central electrode 6 is one tenth of a millimeter.
Conversely and as is easily understood, when the shuttle electrode 20 is in contact with the shuttle electrode stopper on the chamber side 24, the space left between its end on the chamber side 21 and the ground electrode 7 is one tenth of a millimeter while the space left between its end on the cavity side 22 and the central electrode 6 is seven tenths of a millimeter.
Thus, the total length of the electric arc - or otherwise named, of the spark to be produced between the ground electrode 7 and the central electrode 6 is constant, eight tenths of a millimeter, while the distance to be traveled by the shuttle electrode 20 to go from one stop 23, 24 to the other is six tenths of a millimeter.
Thus and advantageously, the electric voltage to be produced to create said electric arc remains constant and close to the values usually used in the context of spark plugs of spark-ignition engines, however, that the greatest length of said arc occurs in the combustion chamber. 11 when the shuttle electrode 20 is in contact with the shuttle electrode stopper on the cavity side 23, and in the stratification cavity 15 when the shuttle electrode 20 is in contact with the shuttle electrode stopper on the chamber side 24.
To understand the operation of the shuttle electrode spark plug 1 according to the invention, it is useful to break down the operation during the four-stroke of the internal combustion engine 2.
First, we will consider that said motor 2 burns a main charge 12 that is practically undiluted and therefore highly burnable. The use of a pilot load 18 is therefore not necessary, which makes it possible to save the compression of said pilot load 18 and to give said motor 2 maximum efficiency in this context.
The shuttle electrode 20 being in contact with the shuttle electrode stop on the cavity side 23, during the intake phase of the internal combustion engine 2, the piston 9 descends into the cylinder 8. The volume of the combustion chamber 11 increases and the pressure in said chamber 11 decreases. A main charge 12 is introduced into the cylinder 8 via the intake pipe 13 of the internal combustion engine 2 through an intake valve 45.
Thus, the pressure which prevails in the combustion chamber 11 temporarily becomes lower than that which prevails in the stratification cavity 15. Consequently, the gases contained in the stratification cavity 15 exert a force on the closure-opening collar 36 which hitherto formed a sealed contact with the shuttle electrode shutter seat 30 with which it cooperates. Such a situation is illustrated in Figure 6.
Subsequent to said effort, the contact between the shutter-opening collar 36 and the shuttle electrode shutter seat 30 is broken and the shuttle electrode 20 moves in the direction of the combustion chamber 11 until that the shutter-opening collar 36 comes into contact with the electrodenette opening seat 32, which is also shown in FIG. 6.
In doing so, gases burned or not from the previous cycle still contained in the stratification cavity 15 escape from the latter to go towards the combustion chamber 11 mainly and respectively via the three longitudinal gas passage channels 35 which the insulating sleeve 25, the torch ignition prechamber 37, and the gas ejection orifices 38.
It will also be noted that during its travel, the opening shutter flange 36 will gradually open the gas passage via the longitudinal gas passage channels 35 by uncovering the gas ejection orifices 38 first partially, then more and more and until completely as it advances towards the shuttle electrode opening seat 32.
The sequence which has just been described makes it possible to find the spark plug with shuttle electrode 1 according to the invention in the situation illustrated in FIG. 3.
The piston 9 having reached its bottom dead center and the inlet valve 45 having closed, said piston 9 begins to rise in the cylinder 8 and to compress the main charge 12. The volume of the combustion chamber 11 decreases and the the pressure prevailing in said chamber 11 increases to the point of becoming higher than that prevailing in the stratification cavity 15.
As a result, the gases contained in the combustion chamber 11 exert a force on the shutter-opening collar 36 which hitherto formed a sealed contact with the seat of the shuttle electrode opening 32 with which it cooperates. Consequently, the shuttle electrode 20 moves until the shutter-opening collar 36 comes into abutment on the electrowash shutter seat 30 to form a tight contact with the latter again. This leads to the situation shown in Figure 4.
It will be noted that in all cases, except during the brief instant during which the shutter-opening collar 36 forms a sealed contact with the shuttle electrode shutter seat 30, it is mainly the dynamic pressure of the gases linked movement of the latter from the stratification cavity 15 towards the combustion chamber 11 or vice versa, which acts on said flange 36 to maneuver the shuttle electrode 20 in translation.
It is understood that the amount of gas which passes through the shutter-opening collar 36 to pass from the combustion chamber 11 to the stratification cavity 15 or vice versa depends on the movement of the piston 9 but also, on the ratio between first firstly, the total volume of said gas contained in the cylinder 8 and the combustion chamber 11, and secondly, the total volume of said gas contained in the torch ignition prechamber 37, the longitudinal gas passage channels 35 , the stratification cavity 15, the gas injection channels 41, the annular pilot charge injection chamber 39, and the injector outlet duct 42.
It will also be noted that when the shutter-opening collar 36 forms a tight contact with the shuttle electrode opening seat 32 and while the pressure in the combustion chamber 11 rises, the total section exposed by said collar 36 at the pressure of gases contained in said chamber 11 is significantly greater than the total section of the gas ejection orifices 38. This makes it possible to produce sufficient force on the shuttle electrode 20 to push it in the direction of the cavity stratification 15 during the ascent of the piston 9 in the cylinder 8, at a sufficiently high speed.
As the piston 9 continues to rise in the cylinder 8, it compresses the main load 12, which places the opening shutter collar 36 more and more strongly on the shuttle electrode shutter seat 30.
When the main charge 12 is to be ignited, a high voltage current is applied to the central electrode 6 so that an electric arc of one tenth of a millimeter is produced between said central electrode 6 and the end on the cavity side 22 of the shuttle electrode 20, while a second electric arc of seven tenths of a millimeter is produced between the ground electrode 7 and the chamber side end 21 of the shuttle electrode 20. This situation is shown in FIG. 5.
The burnable gases possibly present in the stratification cavity 15 are not ignited because the distance between the central electrode 6 and the cavity side end 22 of the shuttle electrode 20 is insufficient. In fact, said distance is less than the thickness of the flame trapping layer known per se which lines the internal surface of the stratification cavity 15.
The main charge 12 is ignited under conditions similar to those found in any spark ignition engine operating with a main charge 12 practically undiluted and highly burnable.
The piston 9 having crossed its Top Dead Center, it descends into the cylinder 8 to relax the gases constituting the main charge 12 which are now hot. Said piston 9 operates this descent while producing work on a crankshaft 43 which has the internal combustion engine 2, by means of a connecting rod 44 with which said crankshaft 43 cooperates.
The piston 9 arriving near its bottom dead center, the exhaust valve 46 of the internal combustion engine 2 opens and the burnt gases begin to escape from the combustion chamber 11 via the exhaust duct 14. The pressure prevailing in said chamber 11 drops suddenly to the point of rapidly becoming lower than that prevailing in the stratification cavity 15.
The gases contained in the stratification cavity 15 then exert a force on the shutter-opening collar 36 which hitherto formed a sealed contact with the shutter seat of the shuttle electrode 30 with which it cooperates.
Subsequent to said effort and as shown in FIG. 6, the shuttle electrode 20 moves in the direction of the combustion chamber 11 until the shutter-opening collar 36 comes into contact with the electrode-opening seat. 32, or not if the time left for this movement is too short because, in fact, the piston 9 having exceeded its bottom dead center, it begins to expel the burnt gases from the combustion chamber 11 via the exhaust duct 14.
During the exhaust stroke of the piston 9, it is understood that the pressure of the gases will substantially rise in the combustion chamber 11 to the point that the shuttle electrode 20 can start again in the direction of the stratification cavity 15 and this, until whether the shutter-opening collar 36 comes into contact with the shuttle electrode shutter seat 30 or not. This situation, which may occur in whole or in part, is illustrated in FIG. 4.
Once the piston 9 has again reached its Top Dead Center at the end of the exhaust stroke, the internal combustion engine 2 can carry out a new thermodynamic four-stroke cycle which it is understood that the ignition can be operated by the spark plug with electrode-shuttle 1 according to the invention under conditions similar to those found in any said spark-ignition engine 2 equipped with a conventional spark plug, and operating a main charge 12 little or not diluted and therefore highly burnable.
The advantages of the spark plug with a shuttle electrode 1 according to the invention are effectively noticeable only when the main charge 12 is greatly diluted, for example with cooled recirculated exhaust gases called "cooled EGR". Indeed, the resulting gas mixture is more resistant to ignition and is in no way favorable to a rapid development of its combustion in the three-dimensional space of the combustion chamber 11.
Under such conditions, the use of a pilot charge 18 is recommended provided that said charge 18 is effective not only in initiating combustion, but also in developing said combustion in the shortest possible time, these two objectives being directly served by the spark plug with shuttle electrode 1 according to the invention.
According to the non-limiting example of embodiment of the spark plug spark plug 1 taken here to illustrate its operation, we will assume that the pilot charge 18 contains a percent of the fuel that contains the main charge 12.
As before, the shuttle electrode 20 being in contact with the shuttle electrode stop on the cavity side 23, during the intake phase of said engine 2, the piston 9 descends into the cylinder 8.
The volume of the combustion chamber 11 increases and the pressure prevailing in said chamber 11 decreases. A main charge 12 highly diluted with cooled EGR is introduced into the cylinder 8 by the intake valve 45 via the intake duct 13 of the internal combustion engine 2.
As before, the pressure which prevails in the combustion chamber 11 temporarily becomes lower than that which prevails in the stratification cavity 15. Consequently, the gases contained in the stratification cavity 15 exert a force on the closure flange. opening 36 which hitherto formed a sealed contact with the shutter seat of the shuttle electrode 30 with which it cooperates.
Following this effort and as illustrated in FIG. 6, the contact between the shutter-opening collar 36 and the shuttle electrode shutter seat 30 is broken and the shuttle electrode 20 moves in the direction of the combustion chamber 11 until the shutter-opening collar 36 comes into contact with the shuttle electrode opening seat 32.
In doing so, gases burned or not from the previous cycle still contained in the stratification cavity 15 escape from the latter to go towards the combustion chamber 11 respectively via the three longitudinal gas passage channels 35 which the insulating sleeve comprises. 25, the torch ignition prechamber 37, and the eight gas ejection orifices 38.
The piston 9 having reached its bottom dead center and the inlet valve 45 having closed, said piston 9 begins to rise in the cylinder 8 and to compress the main charge 12 greatly diluted with cooled EGR. The volume of the combustion chamber 11 decreases and the pressure which prevails in said chamber 11 rises to the point of becoming higher than that which prevails in the stratification cavity 15.
As a result, the gases contained in the combustion chamber 11 exert a force on the shutter-opening collar 36 which hitherto formed a sealed contact with the seat of the shuttle electrode opening 32 with which it cooperates. Consequently, and as illustrated in FIG. 4, the shuttle electrode 20 moves rapidly until the shutter-opening collar 36 abuts on the shuttle electrode shutter seat 30 to form with the latter a new waterproof contact.
The piston 9 continuing to rise in the cylinder 8, the pressure prevailing in the combustion chamber 11 continues to rise, however that the pressure prevailing in the stratification cavity 15 no longer rises and retains the value it had at the time the collar shutter-opening 36 came into abutment on the shuttle electrode shutter seat 30 to form a tight contact with the latter.
The stratification cavity 15 now forms a protected volume in which the gases contained in the combustion chamber 11 can no longer penetrate.
It is from this instant that the stratification injector 17 begins to inject a pilot charge 18 consisting of an oxidizer-fuel mixture AF which is easily flammable into the stratification cavity 15, via the injector outlet duct 42, and via the annular pilot charge injection chamber 39 arranged in the threaded spark plug well 40.
As seen in Figures 2 to 12, this is made possible by the fact that the annular pilot charge injection chamber 39 communicates with the stratification cavity 15 by means - according to this non-limiting example - of eight channels of gas injection 41 arranged radially in the metal base 4 at the level of the annular pilot charge injection chamber 39.
Since the stratification cavity 15 initially forms a closed and protected volume, the easily flammable oxidant-fuel mixture AF which makes up the pilot charge 18 does not dilute in any way with the low-flammable gases since it is highly diluted with cooled EGR, the main load 12 is constituted.
Only residual gases diluted with EGR remain which have been introduced into the stratification cavity 15 before the shutter-opening collar 36 has come into abutment on the shuttle electrode shutter seat 30, said gases diluted representing only a few percent of the pilot charge 18.
It will be noted that the start of the injection of the pilot charge 18 into the stratification cavity 15 by the stratification injector 17 was triggered on the order of a management computer not shown in the internal combustion engine 2, taking into account of the dynamics and of the flow rate of said injector 17, and so that the pressure prevailing in said cavity 15 becomes greater than that prevailing in combustion chamber 11 only a few degrees of rotation of crankshaft 43 before it has to be ignited the main load 12.
When effectively, the pressure prevailing in the stratification cavity 15 becomes greater than that prevailing in the combustion chamber 11, a force is exerted on the shutter-opening collar 36 by the gases mainly consisting of oxidant-fuel mixture AF easily flammable .
It follows from this that said flange 36 moves rapidly in the direction of the combustion chamber 11 to come into abutment on the seat of opening of electrodenavette 32 and to form with the latter a sealed contact. This situation is clearly illustrated in Figure 7.
During its movement, the shutter-opening collar 36 has left a small portion of the readily flammable oxidant-fuel mixture AF which constitutes the pilot charge 18 to escape mainly via the gas ejection orifices 38.
Once in contact with the shuttle electrode opening seat 32, said flange 36 has in fact moved the cavity side end 22 of the shuttle electrode 20 to seven tenths of a millimeter from the central electrode 6 so that a high voltage current can now be applied to the central electrode 6 so that an electric arc of seven tenths of a millimeter is produced between said central electrode 6 and the cavity side end 22 of the shuttle electrode 20 while a second electric arc of a tenth of a millimeter is produced between the ground electrode 7 and the chamber side end 21 of the shuttle electrode 20. This situation is illustrated in FIG. 8.
The pilot charge 18 being locally subjected to the heat of the spark thus created and the fact that it mainly consists of oxidizer-fuel mixture AF easily flammable, it ignites quickly while the pressure rises violently in the stratification cavity 15 and in the annular pilot charge injection chamber 39 at several bars above the pressure prevailing at the same time in the combustion chamber 11.
It follows from this that an additional unburnt fraction of the pilot charge 18 is found ejected into the combustion chamber 11 via the eight gas ejection orifices 38, said fraction being immediately followed by torches of burning gases which put it with fire, said torches also igniting the part of the gases constituting the pilot charge 18 which has been ejected via the gas ejection orifices 38 before the spark is triggered, as shown in FIG. 7.
This particular configuration has several advantages, all serving the most efficient firing of the main charge 12 with the pilot charge 18, the latter being the smallest possible in order to minimize the energy cost of compression, in particular by means of the compressor. stratification 19.
First of all and as we have seen, the spark plug with shuttle electrode 1 according to the invention makes it possible to avoid any excessive dispersion of the pilot charge 18 in the main charge 12 during the injection of said charge pilot 18 and before the firing of the latter.
Next, the spark plug with shuttle electrode 1 according to the invention allows a few microseconds for a portion of the pilot charge 18 to penetrate into the main charge 12 in order to enrich it very locally with an oxidizable fuel AF fuel mixture that is easily flammable before putting to fire said part by means of burning gas torches. This feature makes it possible to avoid that too much heat is transferred in pure loss by the hot gases to the internal walls of the stratification cavity 15 and to those in particular of the longitudinal gas passage channels 35, of the ignition pre-chamber by torch. 37 and gas ejection ports 38.
In addition, as clearly shown in FIG. 8, the hot gases expelled by the eight gas ejection orifices 38 arranged radially in the protruding ejection dome 47 form torches of hot gases which ignite the main charge 12 in multiple locations in the combustion chamber 11, the combustion of said charge 12 then developing radially from the periphery of said chamber 11 towards the center of said chamber 11, and tangentially between each said torch.
The strong local turbulence which results from the penetration of said torches into the volume of the combustion chamber 11 also promotes the folding of the flame front generated by each said torch, which further increases their effectiveness in promoting rapid combustion of the charge. main 12.
It will be noted in passing that the greater the volume of gas comprised between the central electrode 6 and the gas ejection orifices 38 is greater relative to the volume of gas comprised between the outlet of the stratification injector 17 and said central electrode 6, the greater the mass of non-burned AF oxidizer-fuel mixture expelled by the gas ejection orifices 38 before the formation of the torches. It is thus possible for engine engineers to choose this ratio by appropriately adapting the positions and relative volumes of the various components of the spark plug electrode 1 according to the invention.
It can also be noted that the spark plug with shuttle electrode 1 according to the invention easily makes it possible to ensure the cleanliness of the protruding ejection dome 47 even when the internal combustion engine 2 operates for a long time with a main charge 12 not diluted and therefore, without resorting to a pilot charge 18.
Indeed, it is well known that the head of the ceramic insulator of the spark plugs which is introduced into the combustion chamber 11 of the spark ignition engines must maintain a temperature ideally between approximately four hundred degrees Celsius to burn any carbon deposits. or charred oil, and eight hundred degrees Celsius temperature above which serious risks of uncontrolled self-ignition of the main charge appear 12.
It can therefore be seen that, according to the particular configuration of the spark plug with shuttle electrode 1 according to the invention which has just been taken as an example to illustrate its operation, it is the protruding ejection dome 47 which can s '' fouling by lack of temperature, or cause uncontrolled self-ignition of main load 12 by excess temperature.
The fouling of the shutter-opening collar 36 does not pose any particular problem in that said collar 36 rises at high temperature when it is licked by the hot gases leaving or entering this stratification cavity 15. last, then cools down once the main load 12 has been burned by resting several times on the shuttle electrode shutter seat 30 with which it cooperates.
When the combustion of the main charge 12 does not require a pilot charge 18, the spark plug with shuttle electrode 1 according to the invention rather behaves like a “cold” spark plug, the protruding ejection dome 47 being directly in contact with the metal base 4 which is in contact with the cylinder head 10 which is usually maintained at around one hundred and ten degrees Celsius when the internal combustion engine 2 has reached its nominal operating temperature.
It will be noted that an air space can be left between a part of the insulating sleeve 25 and the stratification duct 16 so as to limit the heat exchanges between said sleeve 25 and said duct 16. This makes it possible in particular to adjust the average temperature of the protruding ejection dome 47.
Alternatively, it is possible to thermally clean the protruding ejection dome 47 by regularly injecting pilot charges 18 by means of the stratification injector 17 which increase the temperature of said dome 47 until cleaning is obtained research.
Conversely and if this is justified, it is also possible to reduce the temperature of the protruding ejection dome 47 by, for example, injecting air alone into the stratification cavity 15, for example during the intake phases. or exhaust of the internal combustion engine 2.
Note the decisive role of the shuttle electrode 20 in limiting the ignition voltage. Indeed, a high ignition voltage greatly reduces the life of the spark plugs, in particular by corrosion of the electrodes that they contain. In addition, such a voltage calls for massive insulators which are difficult to house and which are prone to break under the effect of temperature.
However, all other things being equal, the required ignition voltage is approximately proportional to the length of the inter-electrode space, however that said voltage must be higher the higher the density of the gases between said electrodes. .
We therefore understand all the difficulty linked to the strategy of cooled EGR which is particularly recommended for spark ignition engines, for example by turbocharger, and which advantageously makes it possible to increase the volumetric ratio of said engines and therefore their average efficiency, with the counterpart to increase the pressure of the main charge 12 at the time of its ignition.
This leads to a high density of gas between the electrodes which argues in favor of bringing the latter together to avoid resorting to an excessively high ignition voltage.
However, as the shuttle electrode 20 moves to alternately leave the greatest length of spark either in the stratification cavity 15 or in the combustion chamber 11, the total length of said spark invariably remains limited to eight tenths of a millimeter according to the example taken here to illustrate the operation of the spark plug with shuttle electrode 1 according to the invention.
The resulting inter-electrode space is always sufficient since if the engine operates a main charge 12 highly diluted with cooled EGR, the spark plug with shuttle electrode 1 according to the invention uses a pilot charge 18 consisting of a highly burnable oxidizer-fuel mixture AF, while if the main charge 12 is not diluted, the inter-electrode space remains in accordance with the profession rules usually adopted by those skilled in the art.
Thus, the shuttle electrode 20 makes it possible to have two separate ignition locations - in this case the stratification cavity 15 and the combustion chamber 11 without the need for either a double ignition system with each its coil and its conducting wires which would become difficult to house, nor an increased total inter-electrode space which would require a high ignition voltage.
The choice of one or the other said place is done automatically according to whether the stratification injector 17 injects or not a pilot charge 18 into the stratification cavity
15.
It will also be noted that the spark plug with shuttle electrode 1 allows the internal combustion engine 2 to operate normally as all said engine 2 operating a main charge 12 not diluted with EGR cooled in the event of compressor failure. stratification 19, of the stratification injector 17 or of any member which would make it possible to supply the stratification cavity 15 with a highly burnable fuel / AF fuel mixture.
In this case, the ignition of the main charge 12 no longer passes through any “passive” prechamber whatsoever - this type of prechamber not being suitable for automobile engines operating at infinitely variable speed and load - but by protruding electrodes compatible with direct gasoline injection, and whose operation is similar to that of ordinary spark plugs as massively produced and marketed in cars.
The variant illustrated in FIGS. 2 to 11 of the embodiment of the spark plug with a shuttle electrode 1 according to the invention has been chosen by way of example to illustrate its operation. It will be noted that another alternative embodiment of said spark plug 1 illustrated in FIGS. 12 to 21 is based on similar principles and that the explanation which has just been given can easily be adapted to said FIGS. 12 to 21 which are classified in the same relative order with respect to said operation.
The possibilities of the spark plug with shuttle electrode 1 according to the invention are not limited to the applications which have just been described and it should moreover be understood that the above description has been given only 'by way of example and that it in no way limits the field of the said invention from which one would not depart by replacing the execution details described everywhere other equivalent.

权利要求:
Claims (20)
[1" id="c-fr-0001]
1. Spark plug with shuttle electrode (1) for internal combustion engine (2), said spark plug (1) comprising at least electrodes (6, 7) and a ceramic insulator (3) housed in a metal base (4) which has a base thread (5), said spark plug (1) also receiving a stratification cavity (15) connected to a combustion chamber (11) which comprises the internal combustion engine (2) by a conduit stratification (16) while a stratification injector (17) can directly or indirectly inject into said cavity (15) a pilot charge (18) previously pressurized, said charge (18) consisting of an oxidizer-fuel mixture AF easily flammable by means of a spark characterized in that it comprises:
• At least one central electrode (6) which opens into the stratification cavity (15);
• At least one shuttle electrode (20) which is wholly or partly made of an electrically conductive material and which is partially or entirely housed with little clearance in the laminating duct (16), said electroduct (20) being inserted between the central electrode (6) and a ground electrode (7) and having firstly, a chamber side end (21) which faces the ground electrode (7) and which is exposed to the pressure prevailing in the combustion chamber (11) and secondly, a cavity end (22) which faces the central electrode (6) and which is exposed to the pressure prevailing in the stratification cavity (15), said electrode- shuttle (20) able to translate in said conduit (16) under the effect of the gas pressure either towards the stratification cavity (15) when the pressure prevailing in the latter is lower than the pressure prevailing in the combustion chamber (1 1), either in the direction of the combustion chamber (11) when the pressure prevailing in the latter is lower than the pressure prevailing in the stratification cavity (15);
• At least one cavity-side shuttle electrode stop (23) which determines the position of the shuttle electrode (20) closest to the laminating cavity (15);
• At least one chamber side shuttle electrode stop (24) which determines the position of the shuttle electrode (20) closest to the combustion chamber (11).
[2" id="c-fr-0002]
2. Spark plug electrode shuttle according to claim 1, characterized in that the shuttle electrode (20) closes all or part of the laminating duct (16) when it is closest to the cavity lamination (15) while it opens said duct (16) over a wider section when it is positioned closest to the combustion chamber (11).
[3" id="c-fr-0003]
3. Spark plug electrode shuttle according to claim 1, characterized in that all or part of the laminating duct (16) comprises an insulating sleeve (25) made of an electrically insulating and / or thermally insulating material and / or refractory, which is integral with said conduit (16), and which is inserted radially and / or axially between the shuttle electrode (20) and said conduit (16), said shuttle electrode (20) being able to translate with the inside said sleeve (25).
[4" id="c-fr-0004]
4. Spark plug electrode shuttle according to claim 3, characterized in that the insulating sleeve (25) has at least one longitudinal gas passage channel (35) which allows the gas to pass from the stratification cavity ( 15) to the combustion chamber (11) or vice versa, said channel (35) being able to be arranged inside and / or on the internal or external surface of said sleeve (25).
[5" id="c-fr-0005]
5. Spark plug electrode shuttle according to claim 1, characterized in that the shuttle electrode (20) consists of an insulating shuttle body (26) made of an electrically insulating material, said body ( 26) being traversed right through in the lengthwise direction by a conductive core (27) of which it is integral, said core (27) being made of an electrically conductive material, a first end (28) of said core (27) facing the ground electrode (7) while a second end (29) of said core (27) faces the central electrode (6).
[6" id="c-fr-0006]
6. Spark plug with shuttle electrode according to claim 1, characterized in that the shuttle electrode stop on the cavity side (23) consists of a shuttle electrode shutter seat (30) arranged in the stratification duct (16) or at any one of the ends of said duct (16), said seat (30) cooperating with a shuttle electrode closure flange (31) which the shuttle electrode (20) has ) at its periphery and / or at its end.
[7" id="c-fr-0007]
7. Spark plug electrode shuttle according to claim 6, characterized in that the shutter electrode shutter (30) and the flange electrode shutter (31) constitute a seal when they are in contact with each other, said seal preventing any gas from passing through said contact when the pressure in the combustion chamber (11) is higher than the pressure in the stratification cavity (15) .
[8" id="c-fr-0008]
8. spark plug with shuttle electrode according to claim 1, characterized in that the shuttle electrode stop chamber side (24) consists of a shuttle electrode opening seat (32) arranged in the laminating duct (16) or at any one of the ends of said duct (16), or in the metal base (4), said seat (32) cooperating with a shuttle electrode opening collar (33) presented by the shuttle electrode (20) at its periphery and / or at its end.
[9" id="c-fr-0009]
9. Spark plug with shuttle electrode according to claim 8, characterized in that the shuttle electrode opening seat (32) and the shuttle electrode opening flange (33) constitute a seal when they are in contact with each other so as to prevent any gas from passing through said contact.
[10" id="c-fr-0010]
10. Spark plug electrode shuttle according to claim 1, characterized in that the shuttle electrode (20) comprises at its periphery guide means (34) which hold said shuttle electrode (20) approximately centered in the stratification duct (16), and approximately in the same longitudinal orientation as said duct (16), regardless of the axial position of said shuttle electrode (20) relative to said duct (16).
[11" id="c-fr-0011]
11. spark plug with shuttle electrode according to claim 1, characterized in that the shuttle electrode (20) comprises at least one longitudinal gas passage channel (35) which allows gases to pass from the cavity of stratification (15) in the combustion chamber (11) or vice versa, said channel (35) being able to be arranged inside and / or on the surface of said shuttle electrode (20) and being able to be produced either on the the entire length of said electroduct (20) while the two ends of said channel (35) open respectively at the end of the chamber side (21) and at the end of the cavity side (22), or , over only a portion of said length while at least one of the two said ends of said channel (35) opens radially from the external surface of the shuttle electrode (20).
[12" id="c-fr-0012]
12. Spark plug electrode shuttle according to claims 6 and 9, characterized in that the shutter flange electrode shuttle (31) and the flange opening electrode shuttle (33) commonly form one and the same shutter-opening collar (36) which defines with the laminating duct (16) - when said shutter-opening collar (36) is in contact with the shuttle electrode opening seat (32 ) - a torch ignition prechamber (37) which communicates simultaneously with the stratification cavity (15) on the one hand, and with the combustion chamber (11) via at least one ejection orifice gases (38) on the other hand.
[13" id="c-fr-0013]
13. Spark plug electrode shuttle according to claims 3 and 12, characterized in that the ignition pre-chamber by torch (37) is arranged inside the insulating sleeve (25).
[14" id="c-fr-0014]
14. Spark plug electrode shuttle according to claim 13, characterized in that the insulating sleeve (25) protrudes from the metal base (4) to present a protruding ejection dome (47) which opens the orifice gas ejection (38).
[15" id="c-fr-0015]
15. Spark plug electrode shuttle according to claim 14, characterized in that the protruding ejection dome (47) is an insert on the insulating sleeve (25).
[16" id="c-fr-0016]
16. Spark plug electrode shuttle according to claim 14, characterized in that the shuttle electrode opening seat (32) is arranged in the protruding ejection dome (47).
[17" id="c-fr-0017]
17. Spark plug electrode shuttle according to claim 12, characterized in that the inner peripheral wall of the ignition prechamber by torch (37) is cylindrical while the opening shutter flange (36) is housed at low radial clearance in said prechamber (37).
[18" id="c-fr-0018]
18. spark plug with shuttle electrode according to claim 6, characterized in that when the shuttle electrode (20) is positioned close to the combustion chamber (11) that is to say either in the vicinity or in contact of the shuttle electrode stopper on the chamber side (24) with which it cooperates, the shuttle electrode shutter collar (31) uncovers at least one gas ejection orifice (38) which brings the cavity into contact stratification (15) with the combustion chamber (11).
[19" id="c-fr-0019]
19. Spark plug with shuttle electrode according to claim 1, characterized in that the stratification injector (17) can directly, or indirectly via an injector outlet duct (42), inject the pilot charge (18 ) in the stratification cavity (15) by means of an annular pilot charge injection chamber (39) which is fitted either in a threaded spark plug well (40) into which the metal base (4) is screwed ) by means of the base thread (5), either on the outer periphery of said metal base (4), or, both in said well (40) and on said periphery of said base (4), said annular chamber (39 ) communicating with the stratification cavity (15) via at least one gas injection channel (41) arranged approximately radially in the metal base (4).
[20" id="c-fr-0020]
20. Spark plug with shuttle electrode according to claim 1, characterized in that the stratification cavity (15) is arranged inside the ceramic insulator (3).
1/13

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同族专利:

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公开号 | 公开日

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EP3560049B1|2020-12-02|

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CN110168825B|2021-04-20|

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FR3060222B1|2019-05-17|

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EP3560049A1|2019-10-30|

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CN110168825A|2019-08-23|

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WO2018104681A1|2018-06-14|

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AU2017371533A1|2019-07-18|

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CA3046393A1|2018-06-14|

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ES2858457T3|2021-09-30|

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KR20190091332A|2019-08-05|

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JP2020501323A|2020-01-16|

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法律状态:
2017-12-22| PLFP| Fee payment|Year of fee payment: 2 |

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2018-06-15| PLSC| Search report ready|Effective date: 20180615 |

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2019-12-26| PLFP| Fee payment|Year of fee payment: 4 |

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2020-12-27| PLFP| Fee payment|Year of fee payment: 5 |

优先权:

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申请号 | 申请日 | 专利标题

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FR1662254A|FR3060222B1|2016-12-09|2016-12-09|ELECTRODE-NAVETTE IGNITION CANDLE|

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FR1662254|2016-12-09|FR1662254A| FR3060222B1|2016-12-09|2016-12-09|ELECTRODE-NAVETTE IGNITION CANDLE|

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EP17825896.8A| EP3560049B1|2016-12-09|2017-12-07|Spark plug with electrode-shuttle|

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KR1020197019467A| KR20190091332A|2016-12-09|2017-12-07|Spark plug with shuttle electrode|

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PCT/FR2017/053453| WO2018104681A1|2016-12-09|2017-12-07|Spark plug with electrode-shuttle|

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CN201780082313.8A| CN110168825B|2016-12-09|2017-12-07|Spark plug with shuttling electrode|

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CA3046393A| CA3046393A1|2016-12-09|2017-12-07|Spark plug with electrode-shuttle|

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ES17825896T| ES2858457T3|2016-12-09|2017-12-07|Electrode Shuttle Spark Plug|

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JP2019530422A| JP2020501323A|2016-12-09|2017-12-07|Spark plug with shuttle electrode|

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AU2017371533A| AU2017371533B2|2016-12-09|2017-12-07|Spark plug with electrode-shuttle|