EP4160001A1 - Allumage à micro-ondes dans une préchambre d'un moteur à combustion interne - Google Patents

Allumage à micro-ondes dans une préchambre d'un moteur à combustion interne Download PDF

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Publication number
EP4160001A1
EP4160001A1 EP21199939.6A EP21199939A EP4160001A1 EP 4160001 A1 EP4160001 A1 EP 4160001A1 EP 21199939 A EP21199939 A EP 21199939A EP 4160001 A1 EP4160001 A1 EP 4160001A1
Authority
EP
European Patent Office
Prior art keywords
cavity
antechamber
combustion chamber
microwave
hollow body
Prior art date
Legal status (The legal status is an assumption and is not a legal conclusion. Google has not performed a legal analysis and makes no representation as to the accuracy of the status listed.)
Withdrawn
Application number
EP21199939.6A
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German (de)
English (en)
Inventor
Raphael Kramer
Heiko Lenz
Jörg Müller
Volker Gallatz
Armin Gallatz
Current Assignee (The listed assignees may be inaccurate. Google has not performed a legal analysis and makes no representation or warranty as to the accuracy of the list.)
Mwi Micro Wave Ignition AG
Original Assignee
Mwi Micro Wave Ignition AG
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 Mwi Micro Wave Ignition AG filed Critical Mwi Micro Wave Ignition AG
Priority to EP21199939.6A priority Critical patent/EP4160001A1/fr
Priority to PCT/EP2022/075089 priority patent/WO2023052082A1/fr
Publication of EP4160001A1 publication Critical patent/EP4160001A1/fr
Withdrawn legal-status Critical Current

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Classifications

    • 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
    • F02P23/045—Other physical ignition means, e.g. using laser rays using electromagnetic microwaves
    • 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
    • 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
    • F02P13/00—Sparking plugs structurally combined with other parts of internal-combustion engines
    • 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
    • H01T13/40—Sparking plugs structurally combined with other devices
    • H01T13/44—Sparking plugs structurally combined with other devices with transformers, e.g. for high-frequency ignition

Definitions

  • the invention relates to a microwave ignition device for igniting an ignitable fluid in a combustion chamber of an internal combustion engine. Furthermore, the invention relates to a method for igniting an ignitable fluid in a combustion chamber of an internal combustion engine and an internal combustion engine having at least one combustion chamber.
  • Ignition devices and ignition methods for igniting an ignitable fluid or fluid mixture in a combustion chamber of an internal combustion engine which provide an antechamber, are basically known from the prior art in various design variants.
  • a prechamber is a small combustion chamber that adjoins an actual combustion chamber of an internal combustion engine and is separated from the actual combustion chamber.
  • the volume bounded by an antechamber, the interior of the antechamber or the inner cavity of the antechamber, is provided and designed in particular to accommodate an ignitable fluid and is typically significantly smaller than the volume of the actual combustion chamber.
  • an antechamber and the actual combustion chamber there is a connection in the form of at least one bore or channel through the outer wall of the antechamber into the interior of the antechamber for the exchange of fluid with the combustion chamber, in particular such that ignitable fluid from the combustion chamber into the antechamber.
  • a small part of the ignitable fluid already in a combustion chamber passes through the at least one bore in the course of a compression process in the combustion chamber, driven by the increase in pressure in the combustion chamber through the at least one bore from the combustion chamber into the antechamber.
  • ignitable fluid in alternative active designs of ignition devices and corresponding ignition methods, provision is made for (additionally) ignitable fluid to be introduced directly into the antechamber or provided in the antechamber.
  • the at least one hole is also used for hot, volatile combustion products to escape from the interior of the antechamber into the combustion chamber after ignition of ignitable fluid in the antechamber.
  • an ignitable fluid is first ignited in the inner cavity of the antechamber.
  • the ignition typically takes place with a conventional spark plug, as is also used for the direct ignition of an ignitable fluid in a combustion chamber of an internal combustion engine.
  • the ignition and subsequent combustion of a fluid in the inner cavity of the antechamber results in the propagation of flare jets, jets of flame, "jets" or the like of hot volatile combustion products through the at least one bore from the inner cavity of the antechamber into the combustion chamber. This then causes in The ignitable fluid in the combustion chamber is also ignited.
  • the ignition of the ignitable fluid in the combustion chamber takes place, in particular when several flare jets spread (if there are several holes in the pre-chamber wall for this purpose) from the inner cavity of the pre-chamber into the combustion chamber in different spatial areas of the Inside the combustion chamber, in contrast to ignition by means of an ignition spark from a conventional spark plug or the like, not only at the location of the ignition spark, but spatially distributed at many points in the combustion chamber, quasi simultaneously.
  • the ignition of an ignitable fluid in a combustion chamber of an internal combustion engine by means of a pre-chamber can in particular the ignition behavior and the Significantly improve the combustion process (including ignition, propagation of the flame front) of lean air-fuel mixtures as corresponding ignitable fluids or fluid mixtures.
  • the excess air of lean air-fuel mixtures leads to unfavorable ignition conditions and thus to insufficient ignition of the air-fuel mixture with conventional ignition with a local ignition spark.
  • the decreasing flame speed results in longer burning times and consequently insufficient burn-through, ie combustion may be incomplete or come to a premature standstill.
  • the ignition and ignition behavior of such lean ignitable fluids can be significantly improved, which improves the efficiency of an internal combustion engine with such an ignition system that burns lean fluids and reduces pollutant emissions, in particular CO -Emissions to be reduced.
  • Ignition devices and ignition methods known from the prior art for igniting a fluid or fluid mixture in a combustion chamber of an internal combustion engine which provide passive and/or active prechamber ignition devices, include conventional spark plugs for igniting the ignitable fluid inside the prechamber.
  • the ignition is typically caused by an ignition spark in the area of the antechamber floor.
  • the antechamber floor designates that end of the interior or inner cavity of an antechamber which is provided at the other end, in its vicinity, at least one borehole for exchanging fluid with and for transferring hot volatile combustion products from the inner cavity of the antechamber into an associated combustion chamber is opposite.
  • the ignition therefore takes place at a point in the interior of the antechamber which is further away from the at least one bore than most other points in the interior.
  • This type of ignition often fails, especially at low load points or at idle speed, because combustion products (residual gas or the like) accumulate in the pre-chamber floor, which counteracts reliable ignition.
  • a remedy could be flushing the antechamber to remove the combustion products create from the prechamber, however, such a solution would significantly increase the complexity of a prechamber ignition device as well as a corresponding prechamber ignition method for an internal combustion engine.
  • Another disadvantage of the ignition devices and ignition methods known from the prior art, which provide prechambers is the short service life of the spark plugs in the prechambers. The spark plugs are only insufficiently cooled and are therefore exposed to high temperatures regularly and over long periods of time. The high temperatures reduce the service life and ensure that the known ignition devices have a short service life.
  • the invention is therefore based on the object of proposing an ignition device and an ignition method for an internal combustion engine which has a significantly increased reliability and durability compared to the solutions known from the prior art and which is safe and reliable for all possible operating states of an internal combustion engine Allows ignition of the ignitable fluid provided for the operation of the internal combustion engine.
  • a microwave ignition device for igniting an ignitable fluid in a combustion chamber of an internal combustion engine according to claim 1, an internal combustion engine according to claim 6 and a method for igniting an ignitable fluid in a combustion chamber of an internal combustion engine according to claim 7.
  • the hollow body can be formed in one or more parts or in segments--if the individual parts or segments from which the hollow body is formed all successively adjoin one another along the preferred longitudinal axis.
  • the preferred longitudinal axis along which the hollow body extends between its two longitudinal ends can be an axis of symmetry for individual segments, i.e. for individual sections of the hollow body along the preferred longitudinal axis, or also for the entire hollow body, but this is by no means mandatory. Symmetry with respect to the preferred longitudinal axis can also be limited to just individual aspects of the design of the hollow body, so the outer design (e.g.
  • the outer circumferential jacket or the like) of the hollow body can be designed approximately symmetrically in a segment that is in this segment inside the Hollow body arranged cavity or partial cavity can deviate from the symmetry of the outer design in this segment or vice versa.
  • the outer design of a segment of the hollow body can be cylindrical or rotationally symmetrical, but the inner cavity or partial cavity in this segment has an elongated cuboid shape, with a preferred longitudinal axis of the cavity or partial cavity (if one can be defined) not coinciding with the preferred longitudinal axis of the hollow body must.
  • the preferred longitudinal axis of the cavity or partial cavity can run parallel to the preferred longitudinal axis of the hollow body at a distance or also enclose an angle with it.
  • hollow body has at least one inner cavity.
  • the hollow body can also have several cavities. If, when there are several cavities inside the hollow body, some of the cavities or all of the cavities are connected to one another, possibly indirectly via at least one other of the cavities, it can be expedient to design this as a coherent cavity with different partial cavities or cavity segments (if the cavities in question successively connect along the preferred longitudinal axis of the hollow body).
  • the hollow body has a jacket or the like as an outer boundary of the hollow body in relation to an exterior, other (cavity) spaces, other bodies, objects, devices, apparatuses, etc. If the hollow body is formed from a number of parts and/or segments, then the casing is divided and/or segmented at least accordingly.
  • the hollow body is preferably made of a material that is at least heat and pressure resistant and has good electrical conductivity, advantageously a metallic material.
  • different parts and/or segments of the hollow body can be made of different materials.
  • Inner walls, inner lateral surfaces or the like as the immediate boundary of the cavity, the cavities and/or the partial cavities of the hollow body can be at least partially provided with coatings that (even further) improve the electrical conductivity.
  • the first end of the hollow body and at the same time the first end of the antechamber of the hollow body is preferably designed in such a way that fluid from the combustion chamber can flow out of a combustion chamber through the at least one bore hole in a compression process in the most streamlined manner possible can reach the antechamber.
  • the antechamber at the first end is particularly preferably also designed in such a way that hot, volatile combustion products are accelerated even further during the transition from the antechamber through the at least one bore) in order to spread the hot, volatile combustion products as far as possible in the form of flare jets (flame ) reach 'Jets' or the like.
  • bores are provided in the wall of the hollow body bordering the antechamber at the first end, these are preferably arranged and aligned in such a way that hot, volatile combustion products can spread through each of the bores in the form of flare jets into different spatial areas of a combustion chamber in order to to be able to ignite the ignitable fluid in the combustion chamber quasi-simultaneously by means of the torch jets at as many points as possible inside the combustion chamber.
  • the antechamber is at least partially designed as a cavity resonator for microwave radiation.
  • the essential characteristic of the antechamber is that it is provided and designed to hold ignitable fluid, which is or can also be ignited in the antechamber and at least partially burns within the antechamber.
  • the essential characteristic of the cavity resonator is that microwave radiation can be coupled into the cavity resonator and when microwave radiation is coupled into the cavity resonator, a standing electromagnetic wave is formed in the cavity resonator.
  • the essential characteristics of the antechamber and the cavity resonator and the resulting formation of the antechamber and the cavity resonator can be combined with one another at least partially (regionally, segmentally) or completely.
  • the antechamber can thus approximately completely enclose or contain the cavity resonator and thus extend, for example, in particular along the preferred longitudinal axis of the hollow body in the axial direction on both sides beyond the cavity resonator.
  • the cavity resonator can also coincide with the antechamber, so that the antechamber and cavity resonator cannot be clearly distinguished from one another, ie the interior (i.e. the respective inner cavity) of the antechamber and cavity resonator is basically the same spatial volume element in the hollow body take in.
  • the cavity resonator can extend in particular along the preferred longitudinal axis of the hollow body to the second end of the hollow body beyond the antechamber.
  • a boundary, wall, edging or the like of the antechamber towards the second end of the hollow body must therefore on the one hand represent an impenetrable barrier, in particular for ignitable fluid that is or can be accommodated in the antechamber, but at the same time must not block the microwave radiation, otherwise the cavity resonator will fail intended function cannot be fulfilled.
  • At least two means for local field enhancement are arranged or formed on the inside surrounding an outer wall of the cavity resonator.
  • Three or more means for local field enhancement are preferably provided.
  • the means for local field enhancement influence the distribution of the electric field in the cavity resonator when microwave radiation is coupled into the cavity resonator and a standing electromagnetic wave forms in the cavity resonator.
  • the means for local field enhancement preferably protrude from the outer peripheral wall of the cavity resonator a little way into the interior/inner cavity of the cavity resonator, approximately essentially in the direction of a center of the cross section of the cavity resonator at the respective position at which the respective means is arranged or formed for the local field increase in relation to the preferred longitudinal direction of the hollow body and/or primarily in the radial direction.
  • the means for local field increase bring about particularly high electric field strengths, particularly in the vicinity of a respective free end of each means for local field increase.
  • the means for local field enhancement are or are arranged or formed where in the cavity resonator depending on the characteristics (in particular wavelength) of the microwave radiation provided in the case of the microwave radiation being coupled into the cavity resonator particularly high electric field strengths are present.
  • the means for local field increase the field distribution in the If necessary change the cavity resonator compared to an identical cavity resonator without such means for local field enhancement.
  • the means for local field enhancement can have the basic form of a more or less pronounced tip protruding into the interior of the cavity resonator from the inner peripheral wall of the cavity resonator. However, such a configuration is by no means necessary or even mandatory.
  • the means for local field increase are arranged in a region or segment of the cavity resonator that coincides with the antechamber (or vice versa). If ignitable fluid is contained in the antechamber and microwave radiation is coupled into the cavity resonator, which in turn leads to the formation of a standing electromagnetic wave in the cavity resonator, one or more flashovers or arcs form at least between the means for local field enhancement by the ignitable fluid, which ignite the ignitable fluid in the antechamber.
  • the flashovers or arcs form depends on many factors, including the detailed design of the means for local field enhancement, their number and their arrangement/distribution around the cavity resonator.
  • An asymmetrical or non-uniform arrangement/distribution of the means for local field enhancement running around the inside of the outer wall of the cavity resonator enables the use of a broader frequency range of microwave radiation.
  • the means for local field enhancement can be designed differently for this purpose, for example by protruding to different extents into the cavity resonator.
  • the means for local field enhancement Due to the arrangement of the means for local field enhancement in an area surrounding (near) the first end of the hollow body and thus at the same time the first end of the antechamber, where the at least one bore is also provided, it is ensured that there is always sufficient (fresh) ignitable fluid in the Area of the means for local field enhancement is located and an ignition of the fluid in the antechambers as well as an immediately subsequent ignition of ignitable fluid in one of the microwave ignition system according to the invention Combustion chamber of an internal combustion engine can be done safely and reliably. This also applies in particular in the case of a longer continuous operating time of the microwave ignition device or of the motor with such a microwave ignition device.
  • a first end of the cavity resonator can coincide with the first end of the antechamber and thus at the same time with the first end of the hollow body.
  • the first end of the cavity resonator can also be arranged at a certain axial distance from the first end of the antechamber/hollow body as a whole inside the antechamber.
  • this should not be understood to mean that a wall or the like extends across the antechamber at this point, which on the one hand would serve as a reflector for microwave radiation, but on the other hand would also divide the antechamber into two separate chambers, which would be rather inexpedient.
  • the antechamber can be designed like a Nozzle can be designed with a cross section that tapers towards the first end. Depending on the wavelength of the intended microwave radiation, this cross-section can become too small for the microwave radiation to propagate further to the first end of the antechamber (cf. cut-off frequency) and thus represents a kind of virtual (reflecting) wall and a corresponding virtual first end of the cavity resonator.
  • the antechamber is spatially separated from the rest of the cavity and/or from all other (partial) cavities of the hollow body by an at least partially microwave-transparent barrier.
  • the microwave-transparent barrier closes off the antechamber in the direction of the second end of the hollow body and, in particular, prevents ignitable fluid and hot, volatile combustion products from flowing out of the antechamber in the direction of the second end of the hollow body and into other parts, areas of the segments of the cavity, which are not part of the antechamber and/or penetrate into other (partial) cavities of the hollow body.
  • the microwave-transparent barrier is preferably resistant to severe, sudden temperature and pressure changes and other loads that are to be expected in the immediate vicinity of a combustion chamber for the combustion of ignitable fluids.
  • the barrier is preferably made of a ceramic material that is transparent to the intended microwave radiation.
  • microwave radiation is coupled into the cavity resonator eccentrically and/or asymmetrically. This breaks the symmetry of the cavity and causes many resonant modes to couple in the cavity. This also considerably reduces the problem with regard to microwave radiation which is or can be coupled into a microwave feed to the cavity resonator, from which microwave radiation can be coupled into the cavity resonator, and possibly also runs further back to a microwave source or is reflected back.
  • a further part of the cavity and/or a further cavity of the hollow body extends between the second end of the hollow body and the cavity resonator and is designed as a microwave waveguide into which microwave radiation can be coupled at the second end.
  • the microwave ignition source includes not only the antechamber and cavity resonator but also a piece of microwave waveguide for guiding microwave radiation from the second end of the hollow body to the cavity resonator, more precisely: to the second end of the cavity resonator.
  • the second end of the cavity resonator and the second end of the hollow body are spaced apart from one another in the axial direction.
  • the second ends of the cavity resonator and the hollow body coincide, optionally also with the second end of the antechamber.
  • the at least one bore has a diameter of between 0.2 mm and 1.3 mm.
  • the specification refers to a hole with a circular cross-section and corresponding cross-sectional area.
  • a corresponding equivalent (identical-sized) circular area should be used.
  • Such particularly small bores are advantageous for improving the ignition behavior of a microwave ignition device according to the invention in combination with an internal combustion engine in which the use of highly charged ignitable fluids is provided. Hydrogen-air (gas) mixtures are mentioned as an example of highly charged ignitable fluids or fluid mixtures.
  • the pressure in the combustion chamber is over 150 bar.
  • the high pressure is associated with a high compression of the ignitable fluid in a combustion chamber of a supercharged internal combustion engine in the course of a compression process in the combustion chamber with a seamless transition to (subsequent) ignition of the ignitable mixture.
  • the high compression typically results in a significantly higher dielectric strength of the ignitable fluid.
  • this inhibits the formation of ignition sparks between the electrodes of the spark plugs.
  • Highly supercharged internal combustion engines with ignition devices known from the prior art therefore suffer from efficiency losses and insufficient running smoothness due to frequent misfires.
  • ignitable fluid in a combustion chamber of an internal combustion engine associated with the microwave ignition device according to the invention is delayed during a compression process with regard to the pressure increase in the antechamber compared to the combustion chamber.
  • the maximum pressure in the antechamber or in the proportion of ignitable substance contained in the antechamber Fluid compared to the associated combustion chamber immediately prior to ignition can thus turn out to be significantly more than an order of magnitude smaller.
  • the dielectric strength of the portion of ignitable fluid contained in the antechamber is also considerably lower than that of the (main) portion of the ignitable fluid contained in the associated combustion chamber. This means that even highly charged internal combustion engines can be safely and reliably ignited by means of a microwave ignition device according to the invention.
  • An internal combustion engine according to the invention with at least one combustion chamber has a microwave ignition system corresponding to one of the configurations of a microwave ignition system according to the invention described above or any combination of these configurations. At least one microwave ignition system according to the invention is preferably assigned to each combustion chamber of such an internal combustion engine.
  • the at least one connection has such a sufficiently small cross section that during a compression process the pressure increase in the combustion chamber in the first region of the cavity compared to the pressure increase in the combustion chamber takes place with a time delay and the maximum pressure immediately before the ignition of a fluid in the first region is no more than one tenth, preferably no more than one twentieth, of the pressure in the combustion chamber.
  • the small cross-section of the connection thus inhibits the flow of ignitable fluid from the combustion chamber into the first area of the cavity in the course of the compression process affecting the combustion chamber to such an extent that up to a point in time immediately before the ignition of the ignitable fluid located in the first area ignitable fluid has reached the first area for safe ignition from the combustion chamber, the pressure and in the first area and thus in the fluid located there and its compression is still considerably lower than in the combustion chamber and the (main) part located there of the ignitable fluid.
  • a time delay in the pressure increase in the first area of the cavity compared to the combustion chamber in the course of a compression process affecting the combustion chamber allows the pressure in the first area of the cavity at the time of maximum compression in the combustion chamber immediately before ignition can be significantly lower than the pressure in the combustion chamber.
  • the pressure in the first region of the cavity can be limited to less than 10 bar.
  • the part of the ignitable fluid located in the first region of the cavity also has a significantly lower dielectric strength with significantly lower compression and a significantly lower pressure compared to the (main) part of the ignitable fluid located in the combustion chamber.
  • FIG 1 an embodiment variant of a microwave ignition device 1 according to the invention is shown schematically in a first longitudinal sectional view.
  • figure 2 shows the microwave ignition device 1 from FIG figure 1 in a further longitudinal sectional view, wherein the sectional plane of this longitudinal sectional view is orthogonal to the sectional plane of the longitudinal sectional view figure 1 is.
  • the basic element of the microwave ignition device 1 is an elongate hollow body 2 that extends between a first or front end 3 and a second or rear end 4 along a preferred longitudinal axis that is not explicitly marked in the figures.
  • the alternative designation of the first end 3 of the hollow body 2 as the front end and the second end 4 as the rear end occurs without restricting generality.
  • the outer basic shape, ie the jacket or the outer jacket surface(s), of the hollow body 2 is essentially rotationally symmetrical to the preferred longitudinal axis.
  • the basic external shape enables the use of the microwave ignition device 1 as a direct replacement for known ignition devices both without a pre-chamber, such as conventional spark plugs, and with a pre-chamber without major changes to existing designs of internal combustion engines.
  • the hollow body 2 has two different cavities 5 and 6, which each extend through different areas of the hollow body 2 along the preferred longitudinal axis and meet at one point along the preferred longitudinal axis and are directly connected to each other. Therefore, one could consider the cavities 5 and 6 as two partial cavities of a single contiguous cavity of the hollow body.
  • the first cavity 5 of the hollow body 2 has a rotationally symmetrical basic shape with the preferred longitudinal axis of the hollow body 2 as the axis of symmetry.
  • the first cavity 5 is designed both partially as an antechamber 9 and partially as a cavity resonator 8, with the antechamber 9 and cavity resonator 8 also partially coinciding.
  • the antechamber 9 extends from the first or front end 3 of the hollow body 2, which is also the first or front end of the antechamber 9, to a pressure window 10.
  • the pressure window 10 is fitted into the first cavity 5 and represents a spatial Barrier between the antechamber 9 and a further partial region of the first cavity 5, the intermediate cavity 11, following the antechamber 9 in the direction of the second end of the hollow body 2, and then adjoining it second cavity 6.
  • the antechamber 9 is provided and designed to accommodate ignitable fluid in its interior.
  • a number of bores 12 are formed in the wall of the antechamber 9 or the hollow body 2, with the Figures 1 and 2 and likewise in all other figures, for the sake of clarity, only some of the bores 12 are explicitly referenced.
  • the bores 12 allow ignitable fluid to pass or flow in from a combustion chamber of an internal combustion engine, to which the microwave ignition system 1 is assigned or can be assigned, into the antechamber 9.
  • the bores 12 allow hot, volatile combustion products to escape from the antechamber 9 into the associated combustion chamber into it after the ignitable fluid contained in the antechamber was ignited in the antechamber.
  • the front part of the antechamber 9, which occupies about a quarter of the entire length of the antechamber 9, is designed to taper towards the first or front end 3 compared to the rest of the antechamber 9. Comparable to a nozzle, this serves to improve the flow of hot, volatile combustion products from the antechamber 9 through the bores 12 also arranged in the front area of the antechamber 9 into an associated combustion chamber of an internal combustion engine.
  • the cavity resonator 8 also includes the pressure window 10 and the intermediate cavity 11 from the first cavity 5 of the hollow body 2.
  • the cavity resonator 8 serves to form a standing electromagnetic wave in its interior.
  • microwave radiation can be coupled into the cavity resonator 8 , with microwave radiation first being coupled into the hollow body 2 at its second or rear end 4 into the second cavity 6 of the hollow body 2 embodied as a microwave waveguide 7 .
  • the pressure window 10 represents a spatial barrier or wall, in particular for ignitable fluid contained in the antechamber and also for hot, volatile combustion products and thus forms the second or rear end of the antechamber 9, it is at the same time arranged in the middle of the cavity resonator 8 Pressure window 10 the intended microwave radiation impede only slightly.
  • the pressure window 10 is therefore made of a microwave-transparent ceramic material that also permanently withstands the conditions in the immediate vicinity of combustion of an ignitable fluid, such as strong, sudden pressure and temperature fluctuations and high peak pressures and peak temperatures.
  • the microwave ignition system 1 in the configuration variant according to FIGS. 1 and 2 is designed, for example, for microwave radiation from the K a band (frequency range from 26.5 GHz to 40 GHz).
  • the microwave waveguide 7 is a WR34 rectangular waveguide.
  • the microwave waveguide 7 extends from the second or rear end 4 of the hollow body 2, which is also the second or rear end of the microwave waveguide 7, to the first cavity 5, where the microwave waveguide 7 is connected with its first or front end to its second or rear End in the cavity resonator 8 and at the same time in the first cavity 5 of the hollow body 5 opens.
  • the mouth of the microwave waveguide 7 in the cavity resonator 8 is somewhat eccentric to the preferred longitudinal axis of the hollow body 2, which in turn is the preferred longitudinal axis or (rotational) symmetry axis of the cavity resonator 8 at the same time.
  • the center of the rectangular cross section of the microwave waveguide 7 coincides with the preferred longitudinal axis
  • the center of the rectangular cross section of the microwave waveguide 7 is at a distance from the preferred longitudinal axis.
  • the first end of the microwave waveguide 7 is slightly lower at the mouth in the cavity resonator 8 than at the second or rear end 4.
  • the microwave waveguide 7 is assigned its own preferred longitudinal axis, the preferred longitudinal axis of the hollow body 2 and the Preferred longitudinal axis of the microwave waveguide 7 a small acute angle and intersect at a point on the second or rear end of the microwave waveguide 7 or the hollow body 2.
  • the eccentric and thus deviating from the symmetry of the cavity resonator 8 confluence of the microwave waveguide 7 in the cavity resonator 8 allows Coupling of many resonant modes of microwave radiation in the Cavity resonator 8 and at the same time significantly reduces the problem of microwave radiation reflected from the cavity resonator 8 back into the microwave waveguide 7 .
  • the outer wall of the cavity resonator 8 runs around the inside, which is also the outer wall of the antechamber 9 and the cavity 5 means for local field increase 13 is formed.
  • the means for local field enhancement 13 protrude into the interior, ie the inner cavity, of the cavity resonator 8 .
  • the means for local field enhancement 13 influence the distribution of the electric field in the cavity resonator 8 when microwave radiation is introduced or coupled into the cavity resonator 8 and a standing electromagnetic wave forms in the cavity resonator 8 .
  • the means for local field increase 13 cause particularly high electric field strengths at a respective free end of each means for local field increase 13, which protrudes into the cavity resonator 8.
  • the means for local field increase 13 are arranged or formed there or are where particularly high electric field strengths are present in the cavity resonator 8 as a function of the characteristics (in particular wavelength) of the microwave radiation provided in the case of the standing electromagnetic wave forming in the cavity resonator 8 by coupling microwave radiation.
  • the means for local field increase may change the field distribution in the cavity resonator 8 compared to an identical cavity resonator 8 without such means for local field increase 13 .
  • a second embodiment variant of a microwave ignition system 1 according to the invention is shown in a respective schematic longitudinal sectional view, the sectional plane of the longitudinal sectional view in figure 4 orthogonal to the section plane of the longitudinal section view in figure 3 is.
  • the eccentricity/asymmetry of the microwave waveguide 7 at the point where it opens into the first cavity 5 or the cavity resonator 8 is somewhat more pronounced.
  • the microwave waveguide 7 also has a rectangular cross section, which, however, tapers continuously (linearly) from the second end 4 to the first end, that is to say towards the opening into the cavity resonator 8 .
  • the means for local field increase 13 are in accordance with the second embodiment variant Figures 3 and 4 through recesses or bores (not explicitly referenced in the figures) in the outer wall from the outside into the wall and extend a little in the radial direction the cavity resonator 8 and thus at the same time into the antechamber 9.
  • the means for local field increase 13 are cylindrical and in this respect do not have a pronounced peak shape.
  • FIG 5 a longitudinal sectional view of a third embodiment variant of a microwave ignition system 1 according to the invention is shown.
  • the third embodiment variant has a simple rectangular microwave waveguide 7 for guiding microwave radiation from the second or rear end of the microwave waveguide 7 or the hollow body 2 to the opening of the microwave waveguide 7 at its first end into the second end of the first cavity 5.
  • the microwave waveguide 7 does not open eccentrically/asymmetrically into the first cavity 5, nor does the cross section of the microwave waveguide 7 change between the two ends figure 5 shown third embodiment of a microwave ignition system 1 according to the invention, the antechamber 9 completely encloses the cavity resonator 8 .
  • the second end of the cavity resonator 9 forms an eccentric or asymmetrical perforated diaphragm 14, ie a (conductive/metallic) partition inserted into the first cavity 5 with an eccentric or asymmetrical to the preferred longitudinal axis of the hollow body 2 and at the same time to the rotational symmetry axis of the cavity resonator 8 Recess that allows entry of microwave radiation into the cavity resonator 8.
  • the perforated diaphragm 14 performs the same function as an eccentrically or asymmetrically arranged opening of the microwave waveguide 7.
  • the microwave ignition system 1 opens the microwave waveguide 7 with its first end not directly in the cavity resonator as in the two variants according to the Figures 1 and 2 or 3 and 4, but in the first cavity 5 of the hollow body 2.
  • the cavity resonator 8 already ends at the pinhole 14 as the second end and thus still within the antechamber 9, the second end of which is the same as in the other two design variants is formed by the interface of the thrust washer 10 facing the first end 3 of the hollow body 2/first cavity 5/prechamber 9.
  • the intermediate cavity 11 for the impedance matching of microwaves during the transition from the microwave waveguide 7 into the first cavity 5 .
  • FIG 6 is a view along the preferred longitudinal axis of a hollow body 2 of a microwave ignition system 1 according to the invention into the interior of the hollow body 2 in the region of its first or front end 3 and thus into the interior of the first hollow body 5/the cavity resonator 8/the antechamber 9 shown.
  • a longitudinal sectional view of an end area or section of the hollow body 2 is shown at its first or front end 3 .
  • the basic shape of the hollow body 2 corresponds at its first or front end 3 to that of the Figures 1 and 2 illustrated first embodiment of a microwave ignition system according to the invention 1.
  • the focus of the representation in figure 6 is due to the design of the means for local field enhancement 13, which is why only a front end section of the hollow body 2 is shown in particular in the longitudinal sectional view.
  • the means for local field enhancement 13 are designed as rectangular webs with an overhang.
  • six identically designed means for local field enhancement 13 are arranged equidistantly spaced around the inside of the outer wall of the first cavity 5/cavity resonator 8/prechamber 9.
  • Figures 7 to 11 are based on the representation in figure 6 12 and 13 show alternative designs of means for local field increase 13.
  • the means for local field increase are all identically designed and arranged equidistantly on the inside around the outer wall of the first cavity 5/cavity resonator 8/prechamber 9.
  • six rectangular, narrow webs with an overhang are provided for local field increase 13 and, in addition, a central dome 15, which also and in combination with the means for local field increase 13 the field distribution in the cavity resonator 8 for generating flashovers (arcs) between the means for local Field increase 13, the means for local field increase 13 and the dome 15 and/or optionally additionally between the means for local field increase 13, the dome 15 and/or the outer wall of the cavity resonator 8 if microwave radiation is coupled into the cavity resonator 8.
  • the dome 15 is also to be regarded as a means for local field enhancement 13, with the dome 15 having its own designation and reference number compared to all other means for local field enhancement 13 shown up to this point in the figures by way of example and without loss of generality due to its different structure was assigned.
  • the basic external shape enables the use of the microwave ignition devices 1 according to the invention shown as an example in the figures in internal combustion engines without major changes to known or existing designs of internal combustion engines.
  • the basic design shown in the figures exemplary designs of microwave spark plugs 1 can be adapted to any size and / or power classes of internal combustion engines.
  • microwave radiation from the K a band (frequency range from 26.5 GHz to 40 GHz) was used.
  • another suitable microwave radiation from a different band for example X-band (frequency range from 7.0 GHz to 11.2 GHz), can be used with appropriate adjustment.

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  • Engineering & Computer Science (AREA)
  • Physics & Mathematics (AREA)
  • Electromagnetism (AREA)
  • Optics & Photonics (AREA)
  • Chemical & Material Sciences (AREA)
  • Combustion & Propulsion (AREA)
  • Mechanical Engineering (AREA)
  • General Engineering & Computer Science (AREA)
  • Combustion Methods Of Internal-Combustion Engines (AREA)
  • Ignition Installations For Internal Combustion Engines (AREA)
EP21199939.6A 2021-09-29 2021-09-29 Allumage à micro-ondes dans une préchambre d'un moteur à combustion interne Withdrawn EP4160001A1 (fr)

Priority Applications (2)

Application Number Priority Date Filing Date Title
EP21199939.6A EP4160001A1 (fr) 2021-09-29 2021-09-29 Allumage à micro-ondes dans une préchambre d'un moteur à combustion interne
PCT/EP2022/075089 WO2023052082A1 (fr) 2021-09-29 2022-09-09 Allumage de préchambre à micro-ondes pour un moteur à combustion interne

Applications Claiming Priority (1)

Application Number Priority Date Filing Date Title
EP21199939.6A EP4160001A1 (fr) 2021-09-29 2021-09-29 Allumage à micro-ondes dans une préchambre d'un moteur à combustion interne

Publications (1)

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EP4160001A1 true EP4160001A1 (fr) 2023-04-05

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EP (1) EP4160001A1 (fr)
WO (1) WO2023052082A1 (fr)

Citations (7)

* Cited by examiner, † Cited by third party
Publication number Priority date Publication date Assignee Title
US3934566A (en) * 1974-08-12 1976-01-27 Ward Michael A V Combustion in an internal combustion engine
US20040100179A1 (en) * 2002-11-25 2004-05-27 Boley William C. Spark plug having an encapsulated electrode gap
JP2009036068A (ja) * 2007-08-01 2009-02-19 Nissan Motor Co Ltd 内燃機関の燃焼制御装置
US7644698B2 (en) * 2007-08-02 2010-01-12 Nissan Motor Co., Ltd. Non-equilibrium plasma discharge type ignition device
CN109209729A (zh) * 2018-09-18 2019-01-15 深圳市奥谱太赫兹技术研究院 一种可应用于发动机燃烧室的微波点火系统及方法
US20200182217A1 (en) * 2018-12-10 2020-06-11 GM Global Technology Operations LLC Combustion ignition devices for an internal combustion engine
US20210131337A1 (en) * 2017-08-25 2021-05-06 Massachusetts Institute Of Technology Alcohol And Plasma Enhanced Prechambers For Higher Efficiency, Lower Emissions Gasoline Engines

Patent Citations (7)

* Cited by examiner, † Cited by third party
Publication number Priority date Publication date Assignee Title
US3934566A (en) * 1974-08-12 1976-01-27 Ward Michael A V Combustion in an internal combustion engine
US20040100179A1 (en) * 2002-11-25 2004-05-27 Boley William C. Spark plug having an encapsulated electrode gap
JP2009036068A (ja) * 2007-08-01 2009-02-19 Nissan Motor Co Ltd 内燃機関の燃焼制御装置
US7644698B2 (en) * 2007-08-02 2010-01-12 Nissan Motor Co., Ltd. Non-equilibrium plasma discharge type ignition device
US20210131337A1 (en) * 2017-08-25 2021-05-06 Massachusetts Institute Of Technology Alcohol And Plasma Enhanced Prechambers For Higher Efficiency, Lower Emissions Gasoline Engines
CN109209729A (zh) * 2018-09-18 2019-01-15 深圳市奥谱太赫兹技术研究院 一种可应用于发动机燃烧室的微波点火系统及方法
US20200182217A1 (en) * 2018-12-10 2020-06-11 GM Global Technology Operations LLC Combustion ignition devices for an internal combustion engine

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