WO2016075361A1 - Moteur à gaz à combustion interne à combustion pauvre comportant un dispositif d'allumage à plasma à décharge à barrière diélectrique à l'intérieur d'une pré-chambre de combustion - Google Patents

Moteur à gaz à combustion interne à combustion pauvre comportant un dispositif d'allumage à plasma à décharge à barrière diélectrique à l'intérieur d'une pré-chambre de combustion Download PDF

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Publication number
WO2016075361A1
WO2016075361A1 PCT/FI2015/050690 FI2015050690W WO2016075361A1 WO 2016075361 A1 WO2016075361 A1 WO 2016075361A1 FI 2015050690 W FI2015050690 W FI 2015050690W WO 2016075361 A1 WO2016075361 A1 WO 2016075361A1
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WO
WIPO (PCT)
Prior art keywords
prechamber
engine
assembly
fuel
internal combustion
Prior art date
Application number
PCT/FI2015/050690
Other languages
English (en)
Inventor
Petri Saari
Jingzhou Yu
Original Assignee
Wärtsilä Finland Oy
Priority date (The priority date is an assumption and is not a legal conclusion. Google has not performed a legal analysis and makes no representation as to the accuracy of the date listed.)
Filing date
Publication date
Application filed by Wärtsilä Finland Oy filed Critical Wärtsilä Finland Oy
Publication of WO2016075361A1 publication Critical patent/WO2016075361A1/fr

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Classifications

    • F—MECHANICAL ENGINEERING; LIGHTING; HEATING; WEAPONS; BLASTING
    • F02—COMBUSTION ENGINES; HOT-GAS OR COMBUSTION-PRODUCT ENGINE PLANTS
    • F02D—CONTROLLING COMBUSTION ENGINES
    • F02D41/00—Electrical control of supply of combustible mixture or its constituents
    • F02D41/0025—Controlling engines characterised by use of non-liquid fuels, pluralities of fuels, or non-fuel substances added to the combustible mixtures
    • F02D41/0027—Controlling engines characterised by use of non-liquid fuels, pluralities of fuels, or non-fuel substances added to the combustible mixtures the fuel being gaseous
    • F—MECHANICAL ENGINEERING; LIGHTING; HEATING; WEAPONS; BLASTING
    • F02—COMBUSTION ENGINES; HOT-GAS OR COMBUSTION-PRODUCT ENGINE PLANTS
    • F02B—INTERNAL-COMBUSTION PISTON ENGINES; COMBUSTION ENGINES IN GENERAL
    • F02B19/00—Engines characterised by precombustion chambers
    • F02B19/12—Engines characterised by precombustion chambers with positive ignition
    • F—MECHANICAL ENGINEERING; LIGHTING; HEATING; WEAPONS; BLASTING
    • F02—COMBUSTION ENGINES; HOT-GAS OR COMBUSTION-PRODUCT ENGINE PLANTS
    • F02D—CONTROLLING COMBUSTION ENGINES
    • F02D19/00—Controlling engines characterised by their use of non-liquid fuels, pluralities of fuels, or non-fuel substances added to the combustible mixtures
    • F02D19/02—Controlling engines characterised by their use of non-liquid fuels, pluralities of fuels, or non-fuel substances added to the combustible mixtures peculiar to engines working with gaseous fuels
    • F—MECHANICAL ENGINEERING; LIGHTING; HEATING; WEAPONS; BLASTING
    • F02—COMBUSTION ENGINES; HOT-GAS OR COMBUSTION-PRODUCT ENGINE PLANTS
    • F02P—IGNITION, OTHER THAN COMPRESSION IGNITION, FOR INTERNAL-COMBUSTION ENGINES; TESTING OF IGNITION TIMING IN COMPRESSION-IGNITION ENGINES
    • F02P23/00—Other ignition
    • F02P23/04—Other physical ignition means, e.g. using laser rays
    • H—ELECTRICITY
    • H01—ELECTRIC ELEMENTS
    • H01T—SPARK GAPS; OVERVOLTAGE ARRESTERS USING SPARK GAPS; SPARKING PLUGS; CORONA DEVICES; GENERATING IONS TO BE INTRODUCED INTO NON-ENCLOSED GASES
    • H01T13/00—Sparking plugs
    • H01T13/50—Sparking plugs having means for ionisation of gap
    • H—ELECTRICITY
    • H01—ELECTRIC ELEMENTS
    • H01T—SPARK GAPS; OVERVOLTAGE ARRESTERS USING SPARK GAPS; SPARKING PLUGS; CORONA DEVICES; GENERATING IONS TO BE INTRODUCED INTO NON-ENCLOSED GASES
    • H01T13/00—Sparking plugs
    • H01T13/54—Sparking plugs having electrodes arranged in a partly-enclosed ignition chamber
    • F—MECHANICAL ENGINEERING; LIGHTING; HEATING; WEAPONS; BLASTING
    • F02—COMBUSTION ENGINES; HOT-GAS OR COMBUSTION-PRODUCT ENGINE PLANTS
    • F02P—IGNITION, OTHER THAN COMPRESSION IGNITION, FOR INTERNAL-COMBUSTION ENGINES; TESTING OF IGNITION TIMING IN COMPRESSION-IGNITION ENGINES
    • F02P9/00—Electric spark ignition control, not otherwise provided for
    • F02P9/002—Control of spark intensity, intensifying, lengthening, suppression
    • F02P9/007—Control of spark intensity, intensifying, lengthening, suppression by supplementary electrical discharge in the pre-ionised electrode interspace of the sparking plug, e.g. plasma jet ignition
    • H—ELECTRICITY
    • H01—ELECTRIC ELEMENTS
    • H01T—SPARK GAPS; OVERVOLTAGE ARRESTERS USING SPARK GAPS; SPARKING PLUGS; CORONA DEVICES; GENERATING IONS TO BE INTRODUCED INTO NON-ENCLOSED GASES
    • H01T13/00—Sparking plugs
    • H01T13/02—Details
    • H01T13/08—Mounting, fixing or sealing of sparking plugs, e.g. in combustion chamber
    • Y—GENERAL TAGGING OF NEW TECHNOLOGICAL DEVELOPMENTS; GENERAL TAGGING OF CROSS-SECTIONAL TECHNOLOGIES SPANNING OVER SEVERAL SECTIONS OF THE IPC; TECHNICAL SUBJECTS COVERED BY FORMER USPC CROSS-REFERENCE ART COLLECTIONS [XRACs] AND DIGESTS
    • Y02—TECHNOLOGIES OR APPLICATIONS FOR MITIGATION OR ADAPTATION AGAINST CLIMATE CHANGE
    • Y02T—CLIMATE CHANGE MITIGATION TECHNOLOGIES RELATED TO TRANSPORTATION
    • Y02T10/00—Road transport of goods or passengers
    • Y02T10/10—Internal combustion engine [ICE] based vehicles
    • Y02T10/12—Improving ICE efficiencies
    • Y—GENERAL TAGGING OF NEW TECHNOLOGICAL DEVELOPMENTS; GENERAL TAGGING OF CROSS-SECTIONAL TECHNOLOGIES SPANNING OVER SEVERAL SECTIONS OF THE IPC; TECHNICAL SUBJECTS COVERED BY FORMER USPC CROSS-REFERENCE ART COLLECTIONS [XRACs] AND DIGESTS
    • Y02—TECHNOLOGIES OR APPLICATIONS FOR MITIGATION OR ADAPTATION AGAINST CLIMATE CHANGE
    • Y02T—CLIMATE CHANGE MITIGATION TECHNOLOGIES RELATED TO TRANSPORTATION
    • Y02T10/00—Road transport of goods or passengers
    • Y02T10/10—Internal combustion engine [ICE] based vehicles
    • Y02T10/30—Use of alternative fuels, e.g. biofuels

Definitions

  • the present invention relates to an internal combustion engine according to the preamble of claim 1 .
  • the present invention relates also to a method of operating an internal combustion piston engine according to the preamble of independent method claim.
  • combustion engines need to have low specific fuel consumption and simultaneously they also need to meet very stringent emission requirements.
  • the combustion temperature can be decreased by using leaner fuel mixture in which the air/fuel ratio is high. In some circumstances, the combustion of lean fuel mixtures may be incomplete.
  • spark plugs are used to generate an electric arc or electric spark and the spark plug may be arranged in the cylinder so as to ignite the fuel-air mixture therein.
  • the disadvantage of using the conventional spark plugs, which may also be called as arc discharges, is that the length of the electric arc is substantially limited in size. Therefore, there can be a number of conventional spark plugs in larger main combustion chambers to ignite the combustible fuel mixture more efficiently over a wider area.
  • an electrical pulse igniting the fuel-air mixture may have duration of several microseconds which initiates an electrical breakdown between the electrodes.
  • the electrical breakdown creates a single conducting channel between the two electrodes and a current, i.e. the spark, starts flowing until the energy in the ignition coil is depleted.
  • the standard spark plug may be placed in the cylinder or in a prechamber which is in connection with the main combustion chamber.
  • the conventional spark plug technology may be used successfully to ignite gas mixture on stoichiometric conditions.
  • EP 2097629 B1 discloses a prechamber arrangement for a piston engine wherein a mixture of fuel and combustion air is ignited by a spark plug arranged in the prechamber.
  • the fuel-air mixture is ignited by high electric field strengths without so- called arc discharge.
  • Prechambers are typically used in lean burn Otto-cycle engines using gas as a fuel.
  • the prechambers may be supplied with a richer fuel mixture whereas the main combustion chamber is supplied with a leaner fuel mixture.
  • FR 2 886 689 A1 proposes also corona ignition in a precombustion chamber, by way of which actual ignition is then effected in the main combustion chamber. Injection of the fuel is effected in such a way that a given propor- tion of the fuel can pass into the precombustion chamber by way of the openings.
  • An internal combustion engine operated in that way tends to ignition misfires in operation.
  • Precombustion chamber ignition is based on the concept that a first fuel/air mixture is ignited in the precombustion chamber and that fuel/air mixture ignited in that way can pass by way of transfer openings into the main combustion chamber of the internal combustion engine where ignition of the actual fuel/air mixture takes place.
  • US 201 1/0100322 A1 discloses approach to ignite the fuel-air mixture using also corona discharge ignition in the cylinder of the engine.
  • US 201 1/0100322 A1 discloses a device for igniting a fuel-air mixture in the main combustion chamber of an internal combustion engine.
  • the device comprises an electrode connected to a voltage source and extending into a prechamber wherein a corona discharge takes place.
  • the fuel-air mixture ignited in the prechamber transfer to the main combustion chamber to ignite the fuel-air mixture therein.
  • the document has its focus on different shapes of the prechamber, the cross-sectional internal surface of which is smaller in the region of the at least one opening than the cross-sectional internal surface in the region in which the electrode passes into the precombustion chamber. Additionally, the document discloses a fluid inlet opening into the precombustion chamber. A fluid can be let in by way of the fluid inlet to flush the precombustion chamber. In the preferred case the fluid inlet is connected to a fuel source as in that way fuel or a fuel/air mixture can be let into the precombustion chamber and the supply of fuel is effected independently of the conventional inlet valves.
  • US 2014/0109886 A1 discloses a system for and a method of provid- ing pulsed power to improve the performance efficiency of the engine. Pulsed power that converts a low-power into a high-power and long-time input into a short-time output is also employed to improve the fuel efficiency.
  • EP 2025927 Another way providing plasma discharge ignition is disclosed in EP 2025927.
  • a spark plug which comprises a first electrode, a second electrode, and an insulating member which is formed from dielectric substance and interposed between the first electrode and the second electrode.
  • a spark plug which comprises a first electrode, a second electrode, and an insulating member which is formed from dielectric substance and interposed between the first electrode and the second electrode.
  • An object of the invention is to provide an internal combustion piston engine and method of operating an internal combustion engine adapted to combust gaseous fuel the performance is considerably improved compared to the prior art solutions. Disclosure of the Invention
  • an internal combustion piston engine adapted to combust gaseous fuel
  • gas admission system having an inlet in connection with each cylinder of the engine opening into an inlet channel thereof, and an ignition assembly configured to ignite fuel mixture in a combustion chamber of the internal combustion piston engine, and a control unit which is provided with executable instructions to provide a lean fuel mixture into a main combustion chamber of the engine for combustion
  • the ignition assembly comprises a prechamber assembly having at least one orifice to provide a flow communication between the prechamber and the main combustion chamber of the engine.
  • the ignition assembly further comprises a dielectric barrier discharge plasma plug assembly having at least two electrodes and a layer of dielectric material between the electrodes and that the prechamber assembly is provided with gaseous fuel inlet controllably opening into the prechamber space.
  • the engine is a large-bore engine where the cylinder bore, or bores, has a diameter ⁇ 180 mm.
  • the diameter refers to the diameter of the cylinder bore.
  • one of at least two electrodes in the dielectric barrier discharge plasma plug assembly is covered by a layer of dielectric material.
  • the prechamber assembly is provided with gaseous fuel inlet controllably opening into the prechamber space and the control unit is provided with executable instructions to provide fuel mixture having ⁇ 1 .0 into the prechamber of the engine for each ignition by controlling the fuel fed into the prechamber via the gas fuel inlet.
  • control unit is provided with executable instructions to provide fuel mixture having ⁇ > 1.0 in the main combustion chamber or the engine and the ignition assembly comprises a dielectric barrier discharge plasma plug assembly having at least two electrodes and a layer of dielectric material between the electrodes.
  • the air-fuel equivalence ratio, ⁇ (lambda) is the ratio of actual air- fuel ratio to stoichiometry for a given mixture.
  • the barrier discharge ignition assembly is such a strong ignition source that it is possible to effectively ignite the lean fuel mixture in the main combustion chamber making use of ignition of the lean fuel mixture in the prechamber. This way it is very effectively reduced the amount of generated NOx emissions of the engine because in both the main combustion chamber and the prechamber lean fuel mixture is used.
  • lean fuel mixture such as a mixture having lambda ⁇ >1 .4 in prechamber equipped barrier discharge ignition assembly may be used to improve the engine performance with reliable ignitability and total low NOx emission originating from the main combustion chamber as well as from the prechamber combustion.
  • the volume of the prechamber is 1- 10 % of the clearance volume of the main combustion chamber.
  • This volume can be called as clearance volume or compressed volume of the engine. So, the clearance volume is the volume remaining in the cylinder above the piston when the piston is at its top dead center position. Even if the piston top, valves and/or cylinder head may have an irregular shape the clearance volume takes into account the exact form of the bordering surfaces, well as cylinder head gasket thickness, whenever it effects on the volume.
  • the volume of the prechamber is defined making use of the clearance volume as the reference volume.
  • the volume of the prechamber is more than 1 ,5 % of the clearance volume of the main combus- tion chamber when the piston is at its top dead center.
  • Object of the invention is also met by method of operating an internal combustion piston engine by combusting gaseous fuel, in which method gaseous fuel is admitted to combustion air via an inlet in connection with each cylinder of the engine in an intake duct thereof, providing a lean fuel mixture having ⁇ > 1 .0 in a main combustion chamber of the engine for combustion, the fuel mixture in the main combustion chamber is ignited by a prechamber.
  • the fuel is ignited by activating a dielectric barrier discharge plasma plug assembly in the prechamber thus providing flame propagation from the prechamber space via at least one orifice into the main combustion chamber of the engine, and that gaseous fuel is admitted directly to the prechamber assembly prior to the ignition.
  • the gaseous fuel is admitted directly to the prechamber assembly such that the fuel mixture has ⁇ 1.0 in the prechamber.
  • the flame jet is arranged to reach at least to a distance within 20 mm, or more preferably within 10 mm from the cylinder inner surface to get enough ignition volume in the main combustion chamber while simultaneously making sure that the flame does not hit the inner surface of the cylinder.
  • the dielectric barrier discharge plasma plug assembly and the prechamber assembly provided with gaseous fuel inlet according to the invention are advantageous arranged in the engine such that the flame jet is capable of reaching at least to a distance within 20 mm, or more preferably within 10 mm from the cylinder inner surface.
  • the barrier discharge may be produced by supplying proper voltage to an electrode pair and covering at least one of them with an insulating material.
  • Proper voltage can be provided e.g. either by high frequency high-voltage generator or by pulsed nanosecond high-voltage generator.
  • the dielectric barrier discharge ignition according to an embodiment of the invention has the capability of avoiding spark formation and transition to arc in streamers channels, at least partly because charged species accumulation on the dielectric layer limits the electric field strength and/or formation in the gas gap between the electrodes and therefore micro discharges lifespan cannot exceed few hundreds of nanoseconds.
  • dielectric barriers can self-limit energy loading into the plasma due to charge accumulation on the dielectric surfaces, which rapidly reduces the voltage across the discharge gap and helps stabilize the plasma. This would be benefit to stabilize the ignition and combustion in the prechamber, and then better engine performance.
  • the current between a cylindrical electrode and a central electrode with dielectric material is very low (less than 1 ampere), Low current is be beneficial to minimize electrode erosion problem.
  • the dielectric material between the electrodes i.e. the barrier limits the discharge current and prevents arcs from forming and allows the plasma region to remain cool and diffuse.
  • the dielectric material is advantageously high temperature resistant e.g. ceramic material, which decreases electrode hot corrosion from high temperature combustion flame in prechamber. This is also beneficial to further improve the combustion in the main combustion chamber, and thus providing also higher BMEP (break mean effective pressure) of the engine.
  • Figure 1 illustrates an internal combustion engine provided with an ignition assembly according to a an embodiment of the invention
  • FIG. 2 illustrates an internal combustion engine provided with an ignition assembly according to another embodiment of the invention
  • Figure 3 illustrates an internal combustion engine provided with an ignition assembly according to another embodiment of the invention
  • Figure 4 illustrates an internal combustion engine provided with an ignition assembly according to another embodiment of the invention
  • FIG. 5 illustrates an internal combustion engine provided with an ignition assembly according to another embodiment of the invention
  • Figure 6 illustrates some embodiments of the dielectric barrier discharge plasma plug assembly applicable to the ignition assembly according to the invention.
  • Figure 1 discloses an internal combustion engine 100, which has been adapted to combust gaseous fuel using a lean burn principle.
  • the engine comprises one or more cylinders 102 and cylinder heads 104, as is known in the art.
  • the cylinder head 10 comprises an inlet channel 50 for introducing air into a main combustion chamber 40 of the engine.
  • the major part of the gaseous fuel used in the engine is introduced to the main combustion chamber as mixed with the air in the inlet channel 50 and in the cylinder 40 of the engine.
  • the inlet channel 50 is provided with at least one inlet valve 45 so as to control a fuel and air flow into the cylinder 40 of the engine.
  • the cylinder head 10 comprises also an exhaust gas channel 52 which is provided with at least one exhaust gas valve 46, respectively.
  • the cylinder head is provided with a gas admission system 75 which is provided with a gas inlet 78 arranged to open into the inlet channel 50 of each of the cylinder.
  • the gas inlet 78 is provided with a valve member 27' by means of which the gas admission into the inlet air may be controlled.
  • the valve member 27' is arranged in vicinity of the inlet 78. The operation of the valve member 27' is arranged controllable by a control unit 62.
  • the engine is provided with an ignition assembly 106 which is configured to ignite a combustible fuel mixture of gaseous fuel in a main combustion chamber of the internal combustion piston engine 100 making use of a pre- chamber assembly in the cylinder head.
  • the ignition assembly 106 comprises a prechamber assembly 14 which has at least one orifice 18 to provide a flow communication between the prechamber and the main combustion chamber of the engine 100.
  • the prechamber assembly 14 is provided with a chamber space in which the ignition is initiated.
  • the ignition assembly 106 further comprises a dielectric barrier discharge plasma plug assembly 22 having at least two electrodes 23, 23' provided with a layer of dielectric material 19 between the electrodes.
  • the prechamber has advantageously a volume which is more than 1 % of the main combustion chamber volume at piston top dead center position.
  • the at least one orifice 18 is arranged at a distance D of at least 90 mm from the cylinder inner surface.
  • the ignition assembly 106 is capable of providing reliable ignition of gaseous fuel - air mixture even in a large diameter cylinder and main combustion chamber, and where a lean air-fuel mixture is provided for combustion.
  • the ignition assembly 106 is adapted to generate a plurality of plasma streamers between the at least two electrodes adapted to the assembly.
  • the ignition assembly 106 comprises a central electrode
  • the cylindrical electrode has a base 20.1 or a first end wall at one end of the sleeve-like part of the cylindrical electrode, through which first end wall the central electrode 23 is extending into the cylindrical space of the central electrode.
  • the central electrode 23 is electrically isolated from the first end wall 20.1 of the cylindrical electrode.
  • the central electrode 23 and the cylindrical electrode 23' are coaxially arranged with each other.
  • the central electrode 23 is covered with a layer 19 of dielectric ma- terial.
  • the layer 19 may be arranged, instead or in addition to the central electrode as shown here, on the surface of the cylindrical electrode 23'.
  • the layer may also be a separate part arranged between the electrodes.
  • the central electrode 23 and the cylindrical electrode 23' are substantially of equal length the cylindrical electrode surrounds the central electrode 23 and has its one end open, via which open end the space inside the central electrode may communicate with the prechamber.
  • both of the electrodes 23, 23' extend into the prechamber 20 from the first end 20.1 of the prechamber.
  • the 24 of the prechamber 20 is adapted to form the throat section where the at least one orifice 18 is arranged.
  • the throat section having smaller cross sectional area than average cross sectional area of the prechamber.
  • the at least one orifice 18 is arranged at the end of the throat section.
  • the prechamber 20 in the figure 1 has a circular cross section at each longitudinal location X in the direction of the central longitudinal axis CL along the electrode 23 towards the sec- ond end of the prechamber 20, perpendicular to the axis CL. In the embodiment of figure 1 there is a gap between the central electrode 23 and the surrounding cylindrical electrode which is constant or equal at each different location.
  • the ignition assembly 106 is adapted to generate a plurality of plasma streamers between a central electrode and cylindrical electrode.
  • the approach of the present invention is to apply a so-called dielectric barrier discharge ignition.
  • generated plasma is a non-equilibrium plasma. It is also referred to as non-thermal or low temperature plasma.
  • the barrier discharge may be produced for example by high frequency high-voltage generator or by pulsed nanosecond high-voltage generator. There is a small gap pro- vided between the electrodes in which the discharge of plasma streamers is generated.
  • the discharge is produced by high-voltage, nanosecond pulse generator, in such a plasma ignition system, after activating the assembly, a number of high voltage pulses is generated, which pulses have duration from 5 nanoseconds to 100 nanoseconds and each of the pulses end before the arc occurs.
  • the dielectric barrier discharge plug assembly generates and delivers fast rise, ultra-short, high-voltage pulses effecting in the prechamber space.
  • the dielectric barrier discharge plug assembly 22 is connected to a voltage source 60 that supplies energy that is the source of voltage pulses generated in the dielectric barrier discharge plug assembly 22.
  • the discharge is produced by high-frequency, high-voltage generator, in such a plasma ignition system, after activating the assembly, high voltage AC voltage is generated, which has frequency ranging from lower radio frequency to microwave frequency, for example 3kHz - 300 GHz.
  • the dielectric barrier discharge plug assembly 22 is connected to a voltage source 60 that supplies energy that is the source of voltage pulses generated in the dielectric barrier discharge plug assembly 22.
  • the gas admission system 75 is provided with a gas inlet 78 arranged to open into the inlet channel 50 of each of the cylinder.
  • the prechamber assembly 14 is provided with a gaseous fuel conduit 25 and an inlet 26 for feeding gaseous fuel directly into the prechamber space 15.
  • the conduit is here arranged in communication with a source of gaseous fuel 70.
  • the conduit 25 is further provided with a valve member 27 which controls the fuel flow into the prechamber space.
  • the ignited fuel mixture i.e. basically the combustion flame passes via the orifices 18 into the main combustion chamber 40, and ignite there the combustible fuel mixture.
  • the valve member 27 is arranged to be controlled by the control unit 63, so that the operation of the valve member 27, i.e. feeding of the fuel directly to the prechamber space is arranged suitably in respect to the activating the dielectric barrier discharge plug assembly.
  • the valve member 27 of the conduit 25 is controlled to open prior to or simultaneously with activating the dielectric barrier discharge plug assembly.
  • the control unit is provided with executable instructions to control the timing of commencing the fuel feel and duration of the fuel feed in synchronized manner with activating the dielectric barrier discharge plug assembly. In this manner it is possible to have optimized circumstances in the prechamber for ignition of fuel.
  • the ignition assembly 106 comprises further a control unit 62 arranged to control the operation of, among other possible entities, a voltage source 60 of the ignition assembly.
  • the control unit 62 of the ignition assembly 106 is provided with executable instructions to provide a lean fuel mixture where the air- fuel equivalence ratio ⁇ > 1 into a main combustion chamber of the engine for combustion by controlling at least the fuel valve 27' admitting fuel into the inlet channel 50.
  • the control unit 62 of the ignition assembly 106 is provided with executable instructions to provide a lean fuel mixture having ⁇ > 1 into prechamber of the engine by controlling at least the fuel valve 27 admitting the fuel into the prechamber space 15.
  • the control unit 62 of the ignition assembly 106 is provided with executable instructions to activate, or in other words trigger, the operation of the dielectric barrier discharge plug assembly 106.
  • the control unit 62 is provided with information for setting the high voltage energy to be used during each ignition when activating the dielectric barrier discharge plug assembly. The information of the proper high voltage energy is made available to the control unit 62 for example such that it is arranged in communication with a storage unit 63 into which the information has been stored. Additionally, the control unit 62 is provided with executable instructions to activate the dielectric barrier discharge plug assembly using the information to generate the plasma. In this connection it is meant by one ignition that a charge intended to combust during one cycle of the cylinder is ignited in one or more stages. It should be understood that the control unit may be a part of engines electric operating system 64.
  • the ignited fuel mixture passes via the orifices 18 into the main combustion chamber 40 and there ignite the actual combustible fuel mixture.
  • the fuel combusted in the main combustion chamber 40 is preferably gaseous fuel.
  • the control unit 62 of the ignition assembly 106 is provided with executable instructions to provide a lean fuel mixture where the fuel mixture has ⁇ > 1.4 into the prechamber.
  • Figure 2 disclosed an internal combustion engine 100 according to an- other embodiment of the invention. Also in this embodiment engine is adapted to combust gaseous fuel using a lean burn principle.
  • the figure 2 refers to those elements shown in figure 1 with corresponding reference numbers.
  • the construction and operation of the embodiment is similar to that of figure 1 except that the cylindrical ground electrode 23' is arranged flush with the inner wall of the prechamber.
  • the sleeve-like part of the cylindrical ground electrode has an open end, the edge of which is arranged on the same level with the inner wall of the prechamber.
  • the central electrode 23 which has an end towards the prechamber and the end is arranged flush with the inner wall of the prechamber.
  • FIG 3 there is shown an internal combustion engine 100 according to another embodiment of the invention. Also in this embodiment engine is adapted to combust gaseous fuel using a lean burn principle.
  • the figure 3 refers to those elements shown in figure 1 with corresponding reference numbers. Otherwise the construction and operation of the embodiment is similar to that of figure 1 except what comes to the construction of the ignition assembly 106.
  • the wall 24 of the prechamber 24 is grounded and arranged to operate as one of the electrodes of the dielectric barrier discharge plasma plug assembly 22.
  • the central electrode 23 of the dielectric barrier discharge plasma plug assembly 22 is extending from the first end wall 20.1 via the prechamber space into the throat section.
  • the central electrode 19 is arranged to the centreline CL of the prechamber.
  • first annular gap B between prechamber wall 24 in the prechamber space 15 and the electrode 19.
  • second annular gap A between prechamber wall 24 in the throat section and the electrode 19.
  • both of the gaps are less than 20 mm but are of different size from each other.
  • the gap B is greater than the gap A.
  • the gap A may be greater than the gap B.
  • FIG 4 shows schematically an internal combustion piston engine 100 which comprises one or more cylinders 102 and cylinder heads 104.
  • the engine is provided with an ignition assembly 106 configured to ignite a combustible fuel mixture of gaseous fuel in a main combustion chamber of the internal combustion piston engine 100 making use of a prechamber assembly 14.
  • the prechamber assembly 14 has at least one orifice 18 to provide a flow communi- cation between the prechamber and the main combustion chamber of the engine 100.
  • the prechamber assembly is provided with a chamber space in which the ignition is initiated.
  • the ignition assembly 106 further comprises a dielectric barrier discharge plug assembly 22 having at least one electrode 23 in communication with the prechamber space 15.
  • the dielectric barrier discharge plug assembly 22 comprises a removably assembled plug 722.
  • the plug 722 comprises a body 724 by means of which the plug 722 may be attached to the prechamber 20.
  • the body 722 is provided with a cavity 726 at its one end which is arranged to open into the prechamber space 15 when installed into the prechamber 20.
  • the body is advantageous provided with outer thread which co-operated with an inner thread in the prechamber 20 by means of which the body and thus the plug 722 may be attached to the prechamber.
  • the plug 722 is also provided with an electrode 23 and an insulator 21 to support and at least partially surround the electrode 23.
  • the electrode 23 is electrically insulated from the body 724, and the prechamber as well, and the body 724 operate as a ground electrode of the assembly.
  • the electrode 23 extends into the cavity 726 of the body and is arranged to it central axis.
  • the cavity 726 is delimited by the wall of the cavity such that the cavity is cylindrical having circular cross section.
  • the length of the cavity 726 and the length of the electrode 23 are substantially equal to each other. In other words the electrode extends from a bottom of the cavity to an edge of the cavity.
  • the cavity is formed inside a sleeve-like part at the end of the body.
  • the ignition assembly 106 is adapted to generate a plurality of plas- ma streamers between the electrode and the cylindrical wall of the cavity 726. In the embodiment of figure 4 the ignition assembly is adapted to generate a plurality of plasma streamers into the cavity space of the plug.
  • the dielectric barrier discharge plug assembly 22 is connected to a voltage source 60 that supplies energy that is the source of voltage pulses generated in the dielectric barrier discharge plug assembly 22.
  • the body 724 and the electrode 23 are arranged to extend into the prechamber space 15 which is beneficial for improving ignition of the fuel/air mixture in the prechamber 20. This is due to the fact that the location of plasma streamers is favourable for ignition.
  • the sleeve-like part of the body 724, which extends into the prechamber, is according to an embodiment of the invention provided with porous or perforated wall section
  • the porous or perforated wall section 725 also accelerates the ignition kernel development from the cavity to the prechamber.
  • the ignition assembly 106 comprises further a control unit 62 and a storage unit 63 arranged to operate similar manner to the embodiment of figure 1.
  • the operation and the components of the assembly corresponds to what is mentioned the reference to figure 1 above.
  • Figure 5 shows an ignition assembly 106 configured to ignite a combustible fuel mixture of gaseous fuel in a main combustion chamber of the internal combustion piston engine 100 making use of a prechamber assembly 14, which is otherwise similar to that shown in figure 5 except that in the embodi- ment of figure 6 the body 722 and the electrode 23 are arranged to extend to be flush with the inner surface of the prechamber space 15 which is beneficial for improving corrosion resistance and cooling the body 722.
  • the ignition assembly 106 comprises further a control unit 62 and a storage unit arranged to operate similar manner to the embodiment of figure 1. Thus the operation and the components of the assembly corresponds to what is mentioned the reference to figure 1 above.
  • FIG 6 there are shown some embodiments of the dielectric barrier discharge plasma plug assembly 22 applicable to the ignition assembly accord- ing to the invention.
  • the central electrode 23 is a pin, bar or alike having plain surface and arranged to a central axis CL of the cylindrical ground electrode 23'.
  • the central electrode 23 is provided with a layer 19 of dielectric material. The layer covers the whole conductive or in practical circum- stances active surface of the electrode.
  • the central electrode 23 is supported by an insulator 21 which surrounds the electrode 23 at the lead-through in the wall of the cylindrical electrode operating as a bushing insulator. This way the electrode 23 is electrically insulated from the body of the cylindrical electrode.
  • the central electrode 23 is provided with radially extending protrusions 23.1.
  • the protrusions 23.1 are also covered with the layer 19 of dielectric material equal to the electrode 19 bar section.
  • the central electrode 23 is a pin, bar or alike having plain surface and arranged to a central axis CL of the cylindrical ground electrode 23' and the cylindrical ground electrode 23' is provided with protrusions 23.2 extending from the surface of the electrode radially towards the centreline CL.
  • the protrusions may comprise a number of pins or planar rings.
  • the cylindrical electrode may according to an embodiment of the invention be provided with porous or perforated wall section as is shown in figure 4. This enhances the fluid communication between the inner space and the cavity 726 e.g. improving the flame propagation.

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  • Engineering & Computer Science (AREA)
  • Chemical & Material Sciences (AREA)
  • Combustion & Propulsion (AREA)
  • Mechanical Engineering (AREA)
  • General Engineering & Computer Science (AREA)
  • Physics & Mathematics (AREA)
  • Optics & Photonics (AREA)
  • Ignition Installations For Internal Combustion Engines (AREA)
  • Spark Plugs (AREA)
  • Combustion Methods Of Internal-Combustion Engines (AREA)

Abstract

L'invention porte sur un moteur à pistons à combustion interne (100), lequel moteur est apte à brûler un carburant gazeux, et lequel comprend un système d'admission de gaz (75) ayant une entrée (78) en liaison avec chaque cylindre du moteur s'ouvrant dans un canal d'entrée (50) de ce dernier, et un ensemble d'allumage (106) configuré de façon à allumer un mélange carburant dans une chambre de combustion du moteur à pistons à combustion interne, et une unité de commande (63) à laquelle sont fournies des instructions exécutables pour fournir un mélange carburant pauvre dans une chambre de combustion principale du moteur pour la combustion, l'ensemble d'allumage comprenant un ensemble de pré-chambre (14) ayant au moins un orifice (18) de façon à produire une communication d'écoulement entre la pré-chambre (14) et la chambre de combustion principale (40) du moteur (100). L'ensemble d'allumage (106) comprend de plus un ensemble de bougie à plasma à décharge à barrière diélectrique (22) ayant au moins deux électrodes (23, 23'), et une couche (19) de matériau diélectrique entre les électrodes, et l'ensemble de pré-chambre (14) comporte une entrée de carburant gazeux (26) s'ouvrant de manière commandée dans l'espace de pré-chambre (15). (FIG. 1)
PCT/FI2015/050690 2014-11-12 2015-10-13 Moteur à gaz à combustion interne à combustion pauvre comportant un dispositif d'allumage à plasma à décharge à barrière diélectrique à l'intérieur d'une pré-chambre de combustion WO2016075361A1 (fr)

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Cited By (10)

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US20180135506A1 (en) * 2016-11-14 2018-05-17 GM Global Technology Operations LLC Combustion ignition device for an internal combustion engine
DE102018125080A1 (de) * 2018-10-10 2020-04-16 Rosenberger Hochfrequenztechnik Gmbh & Co. Kg Zündsystem mit einem durch ein HF-Plasma vergrößerten Zündfunken einer Zündkerze mit einer Vorkammer sowie ein zugehöriges Verfahren
FR3088678A1 (fr) 2018-11-15 2020-05-22 Renault S.A.S. Optimisation des canaux de diffusion de pre-chambre de combustion de moteur thermique
US20200182217A1 (en) * 2018-12-10 2020-06-11 GM Global Technology Operations LLC Combustion ignition devices for an internal combustion engine
FR3106619A1 (fr) 2020-01-27 2021-07-30 Renault S.A.S. Pré-chambre multi-sites
CN113574261A (zh) * 2019-04-11 2021-10-29 曼卡车和巴士欧洲股份公司 用于运行内燃机的方法
CN114423934A (zh) * 2019-11-20 2022-04-29 宝马股份公司 用于外部点火的往复活塞式内燃机的气缸头
CN115217619A (zh) * 2022-03-17 2022-10-21 广州汽车集团股份有限公司 扫气装置及其控制方法、汽车
WO2023183662A1 (fr) * 2022-03-23 2023-09-28 Caterpillar Inc. Moteur alternatif à carburant gazeux et méthodologie de fonctionnement pour la réduction de vitesse de flamme d'hydrogène
US12078095B1 (en) * 2023-06-16 2024-09-03 Saudi Arabian Oil Company Internal pre-chamber (IPC) ignition device for turbulent jet ignition in reciprocating engines

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Cited By (16)

* Cited by examiner, † Cited by third party
Publication number Priority date Publication date Assignee Title
US20180135506A1 (en) * 2016-11-14 2018-05-17 GM Global Technology Operations LLC Combustion ignition device for an internal combustion engine
US10018104B2 (en) * 2016-11-14 2018-07-10 GM Global Technology Operations LLC Combustion ignition device for an internal combustion engine
DE102018125080A1 (de) * 2018-10-10 2020-04-16 Rosenberger Hochfrequenztechnik Gmbh & Co. Kg Zündsystem mit einem durch ein HF-Plasma vergrößerten Zündfunken einer Zündkerze mit einer Vorkammer sowie ein zugehöriges Verfahren
US10830201B2 (en) 2018-10-10 2020-11-10 Volkswagen Aktiengesellschaft Ignition system having a high-frequency plasma-enhanced ignition spark of a spark plug, including an antechamber, and a method associated therewith
FR3088678A1 (fr) 2018-11-15 2020-05-22 Renault S.A.S. Optimisation des canaux de diffusion de pre-chambre de combustion de moteur thermique
US20200182217A1 (en) * 2018-12-10 2020-06-11 GM Global Technology Operations LLC Combustion ignition devices for an internal combustion engine
CN113574261B (zh) * 2019-04-11 2024-04-02 曼卡车和巴士欧洲股份公司 用于运行内燃机的方法
CN113574261A (zh) * 2019-04-11 2021-10-29 曼卡车和巴士欧洲股份公司 用于运行内燃机的方法
CN114423934A (zh) * 2019-11-20 2022-04-29 宝马股份公司 用于外部点火的往复活塞式内燃机的气缸头
CN114423934B (zh) * 2019-11-20 2024-04-26 宝马股份公司 用于外部点火的往复活塞式内燃机的气缸头
FR3106619A1 (fr) 2020-01-27 2021-07-30 Renault S.A.S. Pré-chambre multi-sites
CN115217619A (zh) * 2022-03-17 2022-10-21 广州汽车集团股份有限公司 扫气装置及其控制方法、汽车
CN115217619B (zh) * 2022-03-17 2023-08-08 广州汽车集团股份有限公司 扫气装置及其控制方法、汽车
WO2023183662A1 (fr) * 2022-03-23 2023-09-28 Caterpillar Inc. Moteur alternatif à carburant gazeux et méthodologie de fonctionnement pour la réduction de vitesse de flamme d'hydrogène
US11959414B2 (en) 2022-03-23 2024-04-16 Caterpillar Inc. Gaseous fuel reciprocating engine and operating methodology for reduced hydrogen flame speed
US12078095B1 (en) * 2023-06-16 2024-09-03 Saudi Arabian Oil Company Internal pre-chamber (IPC) ignition device for turbulent jet ignition in reciprocating engines

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