WO2014094988A1

WO2014094988A1 - Ignition device for an internal combustion engine and internal combustion engine having said ignition device

Info

Publication number: WO2014094988A1
Application number: PCT/EP2013/003678
Authority: WO
Inventors: Mario Dittmann; Anko Ernst
Original assignee: Mtu Friedrichshafen Gmbh
Priority date: 2012-12-18
Filing date: 2013-12-05
Publication date: 2014-06-26
Also published as: DE102012223640B4; DE102012223640A1

Abstract

The invention relates to an ignition device (1) for an internal combustion engine, comprising an ignition chamber (5), which is separated from a combustion chamber of a cylinder of an internal combustion engine, said cylinder being associated with the ignition device, and which has a center axis (A), and comprising an ignition region for the ignition of a fuel/air mixture present in the ignition chamber (5), wherein the chamber wall (3) has at least one bore hole (17, 19, 19'), which provides a fluid connection between the ignition chamber (5) and the combustion chamber. The ignition device (1) is characterized by a flow-guiding element (25), which is designed in such a way and arranged in relation to the ignition region in such a way that, substantially, fresh gas flows into the ignition region in a compression stroke of the cylinder.

Description

IGNITION DEVICE FOR A COMBUSTION ENGINE AND

COMBUSTION ENGINE WITH THIS IGNITION DEVICE

The invention relates to an ignition device for an internal combustion engine according to the preamble of claim 1 and an internal combustion engine according to the preamble of claim 12.

Ignition devices of the type discussed here are known. German Offenlegungsschrift DE 101 44 976 A1 discloses an ignition device in the form of a pre-chamber spark plug, which has a cylinder of a cylinder associated with a combustion chamber of a combustion chamber of a combustion chamber

Internal combustion engine divided, comprising a central axis ignition chamber comprises. In the ignition chamber, an ignition region is provided in which a present in the ignition chamber fuel / air mixture is ignited. The prechamber spark plug is designed as an electric spark plug with at least two electrodes, between which an ignition spark is generated at the ignition time. Therefore, in the ignition chamber is a

Ignition arrangement is provided which has a center electrode whose axis of symmetry coincides with the central axis. The ignition assembly also has a

Mass electrode, which is separated by a Zündspalt of the central electrode. During operation of the ignition device or of the internal combustion engine, a high voltage is applied to the center electrode at a predetermined ignition time, so that a spark ignites in the ignition gap from the center electrode to the ground electrode, which is preferably permanently grounded or earthed. As a result, a present in the ignition chamber fuel / air mixture is ignited. The ignition region is therefore arranged in this case in the ignition gap or coincides with the Zündspalt. The

Chamber wall has at least one bore, which provides a fluid connection between the ignition chamber and the combustion chamber. In a compression stroke of the cylinder is fresh gas, so unburned

Fuel / air mixture, inserted from the combustion chamber via the at least one bore in the ignition chamber. This is ignited there to the ignition, wherein the inflamed mixture shoots on the designated as a shot channel, at least one bore into the combustion chamber of the cylinder. In this way, a safe and fast ignition and the most homogeneous possible charge conversion of the mixture is ensured in the combustion chamber. Ultimately, an ignition energy amplification is thus effected, wherein the energy of the mixture amount ignited in the ignition chamber increases the ignition energy via the at least one firing channel can reliably trigger the reaction in the combustion chamber. This is especially important when the

Internal combustion engine to be operated with a strongly lean mixture, which is hardly inflammable in the combustion chamber alone with the ignition energy of a spark plug. In particular, this problem occurs in gas engines, most preferably in lean gas engines.

It turns out that in the ignition chamber always a significant proportion of residual gas from the previous combustion cycle remains. This can be achieved by means of a successful coordination of a volume of the ignition chamber above the ignition gap including a volume surrounding an insulator base of the center electrode and a defined swirl and / or tumble ratio of the compression stroke in the cylinder set by means of the design and arrangement of the at least one bore

Ignition chamber prevailing flow can be well concentrated around the central axis of the ignition chamber. In this case, then the flame retardant residual gas is concentrated in the region of a center of the ignition chamber, while in the field of

Kammerwandurig a high fresh gas content, ie a high proportion of unburned fuel / air mixture prevails. This is advantageous if in the ignition device, a so-called near-wall spark position is realized, wherein typically the chamber wall is connected as a ground electrode.

In Vorkammerzündkerzen, as they emerge for example from DE 101 44 976 A1, but is the ground electrode, which also consists of several

Mass electrode segments may be formed, formed separately from the chamber wall, and the Zündspalt is in a region around the center electrode around intended. It is realized a so-called central spark location. Here it is very unfavorable, if due to the pressure prevailing in the compression stroke

Flow conditions a residual gas content in the central region of the ignition chamber, thus concentrated in the region of the ignition gap, While the FriSöhgasanteil is increased in the chamber wall. Thus, a reliable ignition of the mixture in the ignition gap can hardly be guaranteed.

It also shows that the holes or shot channels known

Prechamber spark plugs are generally arranged and aligned so that tumble and / or swirl flows result in the compression stroke in the ignition chamber. Swirl flows are thereby largely converted into tumble flows in an upper region of an insulator base surrounding the center electrode, so that ultimately an increase in the residual gas concentration in the central region of the ignition chamber can hardly be avoided. An optimal propagation of the flame front is so significantly affected.

This problem does not only arise in connection with electrical

Prechamber. Also in other ignition devices, such as laser spark plugs or corona spark plugs; in which a central Zündiage, so an arrangement of the ignition region is provided in the region of the central axis, a high residual gas concentration in the central region is disadvantageous. In the following, in an electrical ignition device of the type mentioned initially, the ignition gap corresponds to the ignition region and the spark gaps of the ignition layer.

If such a spark plug with central ignition or spark in a

Internal combustion engine used with special gas, namely with a strong

inert gas-containing fuel gas is operated, this problem is exacerbated by the fact that the ignition must be advanced due to the high inert gasoline in the fuel gas at an earlier time. However, less time is available in the compression stroke to reduce residual gas components in the ignition chamber, so that they are once again larger than at a later ignition point. Unfavorable for the ignition behavior is that at an early ignition one

Charge movement in the ignition chamber and thus also in the ignition area opposite a later ignition is increased. The term "charge motion" refers to the strength of the gas flow in the ignition chamber.

The invention is based on the object, an ignition device and a

To provide an internal combustion engine, in which a central ignition position is ensured at the same time safer ignition and higher fresh gas content in the ignition. On this catfish, the efficiency of the engine should be increased because a safe and efficient ignition of a mixture with a high proportion of fresh gas in the ignition takes place.

The object is achieved by an ignition device is provided with the features of claim 1.

This is characterized by a flow-guiding element, which is designed in such a way and arranged relative to the ignition region, that in a compression stroke of the cylinder substantially fresh gas flows in the ignition region. In particular, it is provided that the flow guide causes an opposing flow is avoided in the ignition, in the fresh gas flowing out of the combustion chamber in a first direction and at the same time from a volume above the ignition range coming residual gas in a second, to the first direction

opposite direction, flows through the ignition area. Rather, that is

Flow guide preferably arranged and designed so that the

Fresh gas flow through the ignition is not affected as possible, while at the same time the residual gas flow is conducted past the ignition. In this way, the ignition area is flushed very efficiently with fresh gas and also has in the

Ignition point on a high fresh gas concentration. This is an efficient, the efficiency of the engine increasing ignition in the ignition

guaranteed.

An ignition device is preferred, which is characterized in that it comprises an ignition arrangement for igniting the present in the ignition chamber fuel / air mixture in the ignition chamber, wherein the ignition assembly is a a

Having symmetry axis having center electrode whose axis of symmetry coincides with the central axis, wherein the ignition assembly further at least one through having a spark gap spaced from the center electrode ground electrode. The ignition region is arranged in this case in the ignition gap, or can be equated with the Zündspalt. In this case, the flow-guiding element is designed in such a way and arranged relative to the ignition arrangement that in a

Compression stroke of the cylinder substantially fresh gas flows in the ignition gap. The ignition device is in this case as an electrical ignition device for ignition caused by a between the center electrode and the ground electrode

Sparkover formed. This is an opposite flow in the

Ignition gap avoided, and a fresh gas flow through the spark gap is not affected as possible, while the residual gas flow is conducted past the spark gap. The ignition gap is flushed so efficiently with fresh gas, so that it is also in the

Ignition point has a high fresh gas concentration. An efficient, the

Efficiency of the combustion engine increasing ignition in the ignition gap is gewähleistet.

Particularly preferably, the flow guide is arranged and designed so that it covers the spark gap - seen in the radial direction - and preferably even protrudes beyond it. In this case, the flow-guiding element is preferably arranged on a side of the ignition gap facing away from the combustion chamber or the chamber wall, wherein fresh gas can readily flow into the ignition gap from the side of the combustion chamber, ie from the opposite direction

approaching residual gas is prevented by the flow guide on flowing into the ignition gap or is deflected away from this.

It is preferably provided that, viewed in the radial direction, the flow guide element expands along the central axis. It thus forms a kind of ascending ramp to the ignition gap, through which contrary to

Fresh gas flow to the ignition gap flowing residual gas - seen in the radial direction - is directed away from this.

In this case, an axial direction is responsive to a direction which extends along the center axis of the ignition chamber or along the axis of symmetry of the center electrode. A radial direction refers to a direction perpendicular to the

Central axis stands. A circumferential direction responds to a direction which the 6

Center axis of the ignition chamber or the axis of symmetry of the center electrode concentrically surrounds.

Thus, it is prevented by means of the flow guide, that form in the ignition gap two opposing flows in the compression stroke, namely eirie from below approaching fresh gas flow on the one hand, and one from above

oncoming flow of residual gas on the other. Rather, the residual gas flow is deflected by the flow guide - seen in the radial direction - so that it does not pass through the spark gap.

In this context, the wording "below" refers to a side facing the combustion chamber, while the wording "above" responds to a side facing away from the combustion chamber-seen along the central axis. In the compression stroke is therefore the

Fresh gas flow "from below", namely from the combustion chamber, while the residual gas flow substantially "from above" results, namely from a

Insulator surrounding volume above the spark gap.

An ignition device is preferred, which is characterized in that the flow guide is arranged on the center electrode. It is possible that the flow guide is formed as a separate part which is joined to the center electrode or otherwise secured thereto. However, the flow guide element is preferably formed integrally with the center electrode and is preferably provided as a radial projection of a lateral surface thereof. It is - seen in the direction of the central axis - formed above the spark gap to those already described

To be able to guarantee flow conditions. As already mentioned, it preferably completely covers the ignition gap or protrudes beyond it, viewed in the radial direction.

In another embodiment, however, it is also possible that the flow guide does not completely cover the spark gap. Depending on its other geometric design, it may be sufficient that the

Flow guide only partially covers the spark gap, while still from the top approaching residual gas efficiently and to a sufficient extent of the Flow guide - seen in the radial direction - is directed away from the spark gap.

A - measured in the axial direction - distance of the integrally formed with the center electrode Strömungsleitelements to the ignition gap is preferably selected so that no flashover in the region of the Strömungsleitelements adjusts when the center electrode is subjected to high voltage. Rather, the distance is preferably selected so that spark gaps occur only in the region of the ignition gap. For efficient operation of the ignition device, it is important to avoid sparks occurring outside of the ignition gap.

The center electrode is preferably encompassed in regions by an insulator foot. In an alternative embodiment of the ignition device is now provided that the flow guide is not provided on the center electrode, but on the Isolatorfuß. It is possible that the flow guide is joined as a separate part with the Isolatorfuß or otherwise secured thereto. However, it is preferred that the flow guide is provided integrally with the insulator foot as part thereof. It is preferably designed as a radial projection of a lateral surface of the insulator foot. Also in this case, the flow guide preferably covers the spark gap - as seen in the radial direction - completely

or surpasses this particularly preferred.

An ignition device is also preferred, which is characterized in that the flow guide element is designed as a substantially conical projection of the lateral surface of the center electrode. Alternatively or additionally, it is preferred that the flow guide element is designed as a substantially conical projection of the lateral surface of the insulator foot. In this case, the flow guide is - as otherwise preferably the entire ignition device - rotationally symmetrical about the central axis, wherein particularly preferably a - seen in longitudinal section - triangular projection on the center electrode and / or the Isolatorfuß is provided, wherein the triangular cut surface by rotation to the central axis gives a conical projection overall. The cone preferably opens downwards, that is to say in the direction of the ignition gap, with it in the region of its base surface, ie in the region of its largest diameter, preferably covered and particularly preferably surmounted.

In an alternative embodiment, it is possible that the

In particular, it is possible for the flow-guiding element to comprise more than one projection, the plurality of projections preferably -in

Seen circumferential direction - are arranged symmetrically about the central axis at the same angular distance.

If the flow-guiding element is designed as a substantially conical projection, it preferably has a conical surface which slopes downwards towards the center axis and serves as a flow ramp, the boundary line of which-as seen in longitudinal section-being rectilinear. It is also an embodiment possible in which the conical surface - seen in the direction of the central axis - at least partially curved, in particular convex or concave, so that they - seen in longitudinal section - has no straight boundary, but a curved boundary line. In this case, the course of the boundary line, thus the shape of the lateral surface, can be tuned to a desired flow behavior, in particular of the residual gas flowing past the lateral surface, in order to effectively deflect it away from the ignition gap, as viewed in the radial direction.

An ignition device is preferred, which is characterized in that the conical projection is arranged on the center electrode, preferably provided integrally therewith, wherein it springs directly in the region of an axial end face of the insulator foot and - seen in the axial direction - to the

Mass electrode out, thus down, extended. In this case, an axial end face of the projection, namely the base of the cone - seen in the axial direction - at a distance from the spark gap. This means, in particular, that the axial end face of the projection is spaced from an opposite axial end face of the ground electrode, which delimits the spark gap. In this case, this distance is preferably selected so that no sparkover from the projection to the ground electrode occurs when the center electrode is subjected to a high voltage becomes. This ensures that spark flashovers in the ignition always take place exclusively in the ignition gap.

It is also preferred an ignition device, which is characterized in that the conical projection is arranged on the Isolatorfuß, wherein it has its largest diameter - as seen in the axial direction - preferably at the height of the axial end face of the insulator. Thus, the base of the cone is flush or aligned with the axial end face of the Isolatorfußes provided. The diameter of the conical projection decreases - also seen in the axial direction - pointing away from the ground electrode, ie upwards.

This shows overall that the conical projection, independently of the specific exemplary embodiment, preferably widens downwards, ie towards the ignition gap, so that the conical surface area correspondingly forms a ramp for the residual gas flowing in from above, in order to direct it radially away from the ignition gap ,

An ignition device is also preferred, which is characterized in that the ground electrode is designed as a ring electrode, which surrounds the center electrode, viewed in the circumferential direction. In this case, the ignition gap is preferably as

Annular gap formed, which surrounds the center electrode - seen in the circumferential direction - surrounds. The ring electrode is held by at least one spacer element, in particular a web. The spacer element or the web is preferably fastened to the main body of the prechamber spark plug or to the chamber wall.

It is possible for the ring electrode to comprise individual, separate electrode elements, which are preferably provided at the same angular distance from one another and thus distributed symmetrically around the central axis, as viewed in the circumferential direction. In this case, each individual electrode segment is preferably held by at least one spacer element or web, particularly preferably formed integrally with the spacer element or the web.

It is also possible that the ring electrode is integrally formed as - not seen in the circumferential direction - openwork ring. In this case, it is possible that the ring is held only by a single spacer or a single web becomes. But are preferably - seen in the circumferential direction - preferably symmetrically distributed around the central axis, thus provided at the same angular distance from each other provided spacers or webs, for example, three or four such webs.

It is essential here that at least one free space results around the at least one spacer element or between the individual spacer elements, through which residual gas can flow in the direction of the combustion chamber, ie downwards. Accordingly, while fresh gas flows from below into the ignition gap, residual gas flowing in from above is directed radially outwards through the flow-guiding element away from the ignition gap, where it can flow downwards through the at least one free space. Thus, the flow paths for the fresh gas on the one hand and the residual gas on the other hand are separated from each other, with only the flow path for the fresh gas through the spark gap leads. In this way, it is effectively avoided that the fresh gas flow on the one hand and the residual gas flow on the other hand encounter each other in the ignition gap, otherwise the fresh gas concentration in the ignition at the ignition

Ignition gap would be lowered.

It is also preferred an ignition device, which is designed as a laser spark plug. Here, the fuel / air mixture is ignited in the ignition by at least one laser beam. If a central ignition point is provided, it is advantageous if the flow-guiding element causes substantially fresh gas to flow in the ignition region. Since no insulator base and no center electrode are available for arranging the flow guide element in a laser spark plug, at least one holding element, in particular one, is preferably in the ignition chamber

Holding structure, provided on which the flow guide is arranged. In a preferred embodiment, it is provided that the holding element is designed as a cage structure, wherein it is in particular in its shape as a

Ring electrode formed mass electrode can be modeled. In any case, it is possible with the aid of the at least one retaining element to arrange the flow-guiding element in the ignition chamber in such a way that a residual gas flow is conducted away from the ignition region, while fresh gas flows essentially in the ignition region.

It is also an ignition preferred, which is designed as a corona spark plug. Here, the fuel / air mixture is through one of a corona electrode outgoing corpna discharge ignited. Preferably, the corona electrode is partially surrounded by an insulator foot. The strörungsleitelement is preferably arranged on the Isolatorfuß; wherein preferably results in an analogous configuration as in an arrangement of the flow guide on the

Isolator of the center electrode of an electric ignition device with spark ignition. In a corona spark plug, in which a central ignition position is realized, the Strörnungsleitelement has an advantageous effect because a residual gas flow can be directed past the ignition area, while in the ignition substantially fresh gas flows.

It is also preferred an ignition device, which is designed as Vorkammerzündkerze. This is suggested that the ignition chamber forms a structural unit with the spark plug, which is preferably screwed into or otherwise secured to a cylinder head of an internal combustion engine. The chamber wall is preferably formed by a primer cap, which is arranged on a base body of the pre-chamber spark plug or joined to the base body or otherwise attached thereto.

In an alternative embodiment, it is possible that the ignition chamber is formed as part of the cylinder head, wherein the ignition assembly is preferably provided on a spark plug which is screwed into the cylinder head or otherwise secured thereto.

It can still be seen that the heat value of the ignition device increases due to the strörleitleitelement. A portion of the heat absorbed by the ignition device is in turn delivered to the fresh gas, which is beneficial to its

Inflammation behavior affects. This also results in an advantage for the ignition device in comparison to an ignition device which has no Strörnungsleitelement. The increased heat value has a particularly advantageous effect on the ignition behavior of inert gas-containing fuel gases.

If the Strörungsleitelement arranged in the region of the center electrode

or integrally formed with this and in particular as a radial projection of the lateral surface, as well as a conflict of objectives between a

lower energy loss through a thin center electrode on the one hand and a maximum peripheral surface by means of a thick center electrode on the other hand be solved.

The object is also achieved by providing an internal combustion engine having the features of claim 12. This is characterized by an ignition device according to one of the embodiments described above. This realizes in connection with the internal combustion engine, the advantage already in the

Connection with the ignition device have been explained.

An internal combustion engine which is designed as a gas engine is preferred. Particularly preferably, the internal combustion engine is designed as a lean-burn gas engine. in this connection

Realize the advantages associated with the ignition in a special way, since a decreased fresh gas concentration in the ignition gap and there encountered gas flows just by the inert gas of lean gases, especially special gases and a correspondingly advanced ignition in a special way negative effect. Accordingly, the help of the

Ignition achieved advantage here particularly pronounced.

The invention will be explained in more detail below with reference to the drawing. Showing:

Fig. 1 is a schematic partial longitudinal sectional view of a first

Embodiment of an ignition device, and

Fig. 2 is a schematic partial longitudinal sectional view of a second

Embodiment of an ignition device.

Figure 1 shows a schematic partial longitudinal section of an embodiment of an ignition device 1, which is designed as an electric ignition device with spark ignition. In this case, the ignition device 1 is at least in the region shown in Figure 1 substantially rotationally symmetrical about a central axis A, wherein in Figure 1, only a section of the longitudinal sectional plane is shown, which is arranged to the right of the central axis A. The corresponding left area of the longitudinal section plane is obtained by mirroring the representation to the right of the central axis A at this point.

Overall, the geometry of the ignition device 1 results at least in the essentially by rotation about the central axis A. Except for some elements, which will be explained below.

The ignition device 1 has a firing chamber 5 divided off in the mounted state on an internal combustion engine with respect to a combustion chamber of a cylinder assigned to the ignition device 1 by means of a firing chamber 5 which is divided into a kiln wall 3. In this eirie ignition assembly 7 is provided, which comprises a center electrode 9 and a ground electrode 11. The center electrode 9 is rotationally symmetrical about the central axis A, wherein its axis of symmetry coincides with the central axis A. The ground electrode 11 is formed in the illustrated embodiment as a ring electrode, which surrounds the center electrode 9 - seen in the circumferential direction. Between the center electrode 9 and the ground electrode 11 -as seen in the radial direction-an ignition gap 13 of annular design in the illustrated embodiment is arranged, which surrounds the center electrode-seen in the circumferential direction.

The ground electrode 1 is preferably formed as a continuous ring. However, it is also possible that it comprises at least two segments which - in

Seen circumferentially - are arranged at the same angular distance from each other and therefore distributed symmetrically about the central axis A. In any case, the center electrode 11 is held by at least one spacer element 15, preferably at least two, more preferably a plurality of spacer elements 15 is provided, which - seen in the circumferential direction - are arranged at the same angular distance on each other and thus symmetrically distributed about the central axis A.

This shows the following: The statement that the Qeometrie of the ignition device 1 results by rotation of the structure shown about the central axis A, does not apply to the spacer element 15 and only optionally for the ground electrode 11, namely if this is formed as a continuous ring in one piece. In a preferred

Embodiment four spacer elements 15 are each spaced apart by 90 ° - seen in the circumferential direction - so that the entire longitudinal section in the plane of Figure 1 nevertheless results by mirroring the structure shown on the central axis A with respect to the spacer elements 15. It is essential that at least one free space is formed in the region of the at least one spacer element 15, through which gas can flow, in particular in a compression stroke of the cylinder.

In the illustrated embodiment, a plurality of bores are introduced into the chamber wall 3, namely a center bore 9 arranged along the center axis A and two side bores 19, 19 "disposed laterally therefrom. cylindrically symmetrical, particularly preferably formed with a circular cylindrical base.

With regard to the side bores 19, 19 'as well, it can be seen that the ignition device 1 does not result in total around the central axis A as a result of the rotation of the illustrated structure. Rather, a plurality of preferably circular cylindrical bores are preferably introduced into the chamber wall 3, which, however, preferably - viewed in the circumferential direction - are arranged at equal angular intervals, thus symmetrically about the central axis A. They are preferably arranged so that the full

Longitudinal sectional view in the plane of Figure 1 by mirroring the structure shown on the central axis A results.

The central bore 17 and the side bores 19, 19 'provide a fluid connection between the ignition chamber 5 and the combustion chamber, not shown, of the cylinder, also not shown.

In a compression stroke of the cylinder is fresh gas, so unburned

Fuel / air mixture, inserted through the central bore 17 and the side holes 19, 19 'from below from the combustion chamber into the ignition chamber 5. The mixture is ignited at a predetermined ignition timing in an ignition region formed here as ignition gap 13 by applying a high voltage to the center electrode 9, wherein at the same time the ground electrode 11 is grounded, preferably grounded. A spark jumps from the central electrode 9 to the Massenelektfode 11 or vice versa, through which the mixture is ignited in the ignition gap 3. As a result, the mixture is ignited in the entire ignition chamber 5, wherein the inflamed mixture through the wells designated as shot holes 17, 19, 13 003678

15

19 'shoots from the ignition chamber 5 into the combustion chamber and arranged there

Fuel / air mixture safely inflamed.

It turns out that, in particular, combustion products and unburned, inert gas fractions, ie, total residual gas, remain in the ignition chamber 5 after ignition. In particular, the residual gas typically collects in a volume 21, which is arranged above the ignition gap 13 and surrounds an insulator base 23, in which the ittetelektrode 9 is partially arranged.

Essential for an ignition efficiency is that the ignition region, here the Züpdspalt 13 flushed during the Kömpressionstakts as efficiently as possible with fresh gas and freed of residual gas, and that no or hardly any residual gas enters the ignition gap 13 due to the forming in the compression stroke flow. For an efficient ignition namely requires the highest possible concentration of fresh gas in the ignition gap 13. It turns out that in known pre-chamber spark plugs with central spark position in particular by in the volume 21 in Tumbleströmüngen

converted swirl flows ensure that the residual gas is concentrated centrally in the ignition chamber 5 and thus in particular in the ignition range. However, this stands in the way of effective ignition.

In order to improve the ignition behavior of the ignition device 1 and to effect that in the compression stroke of the cylinder substantially fresh gas in the ignition region, here the ignition gap 13 flows, in particular two opposing flows of fresh gas on the one hand and residual gas on the other hand are avoided in the ignition gap 13 is a Strömungsleitelement 25 is provided which is suitably formed and arranged in a suitable manner relative to the ignition assembly 7.

In the embodiment shown in Figure 1, the flow guide 25 is provided on the central electrode 9 and in particular integrally therewith. In particular, it is formed as a radial projection 27 of a lateral surface 29 of the preferably cylindrical center electrode 9. The flow guide 25 is disposed above the spark gap 13. In the illustrated embodiment, the flow guide 25 is also formed as a substantially conical projection 27 which springs directly in the region of an axial end face 31 of the Isolatorfußes 23 and - seen in the direction of the central axis A - expanded to the ground electrode 11 and to the spark gap 13 out , In this case, an axial end face 33 of the projection 27, which can also be considered as the base of the cone formed by the projection 27, a - measured in the axial direction - distance to the spark gap 13 and in particular to an axial end face 35 of the ground electrode 11.

Since the projection 27 is formed of the same material as the center electrode 9 and integrally therewith, it is always at the same potential as this. The axial distance between the end face 33 of the projection 27 and the end face 35 of the ground electrode 11 prevents a spark from jumping over from the land 27 to the ground electrode 11. The distance is thus preferably dimensioned so that no ignition spark skips, but rather that ignition always takes place in the region of the feed gap 13.

A lateral surface 37 of the cone is formed here in a straight line in the sectional view according to FIG. 1 and slopes upward towards the central axis A. As a result, a quasi ramp for the incoming from the top of the volume 21 residual gas is formed so that it is away from the spark gap 13 - seen in the radial direction - and flows through the at least one space in the region of at least one spacer 15 further down.

In an alternative embodiment, it is possible that the lateral surface 37 in the sectional view according to Figure 1 is not rectilinear, but curved, in particular concave or convex curved to the flow behavior of

Influencing residual gases in a suitable manner. In particular, a concave curvature of the lateral surface 37 can cause the residual gas flowing in from above to be effectively accelerated away from the ignition gap 13-radially outwards-that is, away from the central axis A.

During the compression stroke from the bottom into the ignition chamber 5 incoming fresh gas, however, passes unhindered to the ignition gap 13 and can this on 3 003678

17 flow through his way up. Thus, those in opposite

Direction directed flows of the fresh gas on the one hand and the residual gas on the other hand separated from each other by the flow guide 25, wherein substantially fresh gas flows from bottom to top through the Zöndspalt 13, while the flowing from top to bottom residual gas through the flow guide 25 radially outward from the spark gap thirteenth is deflected so that it flows at a greater distance from the central axis A in the region of the at least one spacer element 15 downward.

Thus, at the ignition timing, there is a high Frisean gas concentration in the

Ignition gap 13 before, so that an effective ignition takes place.

It can still be seen that the ignition device in the illustrated

Embodiment is designed as Vorkammerzündkerze, wherein the ignition chamber 5 forms a structural unit with the remaining spark plug, in particular with the ignition assembly 7. Preferably, the chamber wall 3 is arranged as a priming cap on a base body of the prechamber spark plug. In particular, it is preferably formed as a bent sheet, which is penetrated by the central bore 17 and the side holes 19, 19 '.

Figure 2 shows a representation of Figure 1 corresponding partial longitudinal section of a second embodiment of an ignition device 1, which is also designed as an electric ignition device with Funkenzündugg. Identical and functionally identical elements are provided with the same reference numerals, so that reference is made to the preceding description. The embodiment shown in Figure 2 differs from the embodiment shown in Figure 1 in that the flow guide 25 is provided on the insulator 23. It is here as a radial projection 27 of a lateral surface 39 of the

Isolatorfußes 23 formed. The insulator foot 23 is preferably made of ceramic. Since the flow guide 25 is preferably formed integrally here with the Isolatorfuß 23, it comprises the same material, preferably also ceramic.

Also in the embodiment according to FIG. 2, the flow-guiding element 25 is designed as a substantially conical projection of the lateral surface 39. It points the conical projection 27 its largest diameter - seen in the axial direction - at the height of the axial end face 31 of the insulator 23 on. It can also be seen that the axial end surface 33 of the projection 27 is arranged flush with or aligned with the end face 31, or merges into the end face 31 or even formed identically therewith. It is therefore in the illustrated embodiment, preferably at the end face 31 on the one hand and the end face 33 on the other hand to the same area. Starting from the region of its largest diameter, the diameter of the conical projection 27 decreases - as viewed in the axial direction - from the mass electrode 11

groundbreaking, in Figure 2 so upwards.

This ultimately means that the lateral surface 37 in the sectional view according to FIG. 2 again forms a cutting line, which is rectilinear in this case and falls downwards in the direction of the central axis A. Accordingly, in turn, a ramp is formed, which urges from the top of the volume 21 incoming residual gas radially outward from the ignition gap 13 in the region of the spacer element 15. It is also possible in the embodiment shown in Figure 2 that the lateral surface 37 is curved, in particular concave or convex curved, if this is advantageous for the adjusting gas flow.

Incidentally, the mode of operation of the exemplary embodiment according to FIG. 2 is identical to the mode of operation of the exemplary embodiment according to FIG. 1. Here, too, fresh gas flowing in from below from the firebox flows into the ignition gap 13 unhindered, while residual gas coming from above from the volume 21 flows through the

Flow guide 25 is directed radially outward and thus away from the spark gap 13. It then flows through the at least one free space in the region of the spacer element 15 further downwards. As a result, the corresponding streams of fresh gas on the one hand and of residual gas on the other hand separated from each other, wherein substantially fresh gas flows through the ignition gap 13. This results in the advantages already described.

It can be seen that in both exemplary embodiments according to FIGS. 1 and 2, the axial end face 33 of the projection 27 not only covers the ignition gap 13 but also projects beyond the ignition gap 13, ie in the radial direction 03678

19 protrudes. In this way it is particularly efficiently prevented from the top

inflowing residual gas can flow into the ignition gap 13.

In particular, depending on the formation of the lateral surface 37 but can also be provided that the axial end surface 33, the ignition gap 13 is not completely covered, if the approaching from above residual gas is effectively diverted even without this measure of the spark gap 13, so that the desired

Adjusts flow behavior.

The operation of an embodiment of the ignition device 1, which is designed as a laser spark plug or corona spark plug, corresponds to the operation, which in this case in connection with those shown in Figures 1 and 2

Embodiments has been explained. Here, the ignition range corresponds to the ignition gap and the ignition position of the spark position. In particular, the operation of the

Flow guide is also in a laser spark plug and / or in a corona spark plug the same as in the embodiments according to Figures 1 and 2, so reference is made in this respect to their description. It is essential that using the Strömungsleitelements an increased residual gas concentration is avoided in the centrally arranged ignition, with the help of Strömungsleitelements corresponding streams of fresh gas on the one hand and residual gas on the other hand are separated from each other, wherein substantially fresh gas flows through the ignition.

Overall, it turns out that with the help of the ignition device 1 and the

Internal combustion engine is possible to ensure efficient ignition in the ignition region, even with a central ignition position by the flow behavior in the ignition chamber 5 is influenced by means of the flow guide 25 in a suitable manner.

Claims

claims

1. ignition device (1) for an internal combustion engine, with respect to a combustion chamber of the ignition associated cylinder of a

Internal combustion engine by a chamber wall (3) divided, a central axis (A) having ignition chamber (5) with an ignition range for igniting a present in the ignition chamber (5) fuel / air mixture, wherein the

Chamber wall (3) at least one bore (17,19,19 ') which provides a fluid connection between the Zündkämmer (5) and the combustion chamber, characterized by a Strömungsieitelement (25) which is formed and arranged so relative to the ignition region in that, in a compression stroke of the cylinder, substantially fresh gas flows into the ignition region.

2. Ignition device according to claim 1, characterized in that a

Ignition assembly (7) in the ignition chamber (5) is provided, wherein the

Ignition assembly (7) having a symmetry axis center electrode (9) whose axis of symmetry coincides with the central axis (A), wherein the ignition assembly (7) further at least one by a Zündspalt (3) from the central electrode (9) spaced mass electrode (1 1 ), wherein the ignition region is arranged in the ignition gap (13), and wherein the

Strömungsieitelement (25) is formed and arranged so relative to the ignition assembly (7) that in a compression tract of the cylinder in the

Substantial fresh gas flows into the ignition gap (13).

3. Ignition device (1) according to claim 2, characterized in that the

Strömungsieitelement (25) is arranged on the central electrode (9), wherein it preferably as a radial projection of a lateral surface (29) of the central electrode (9) - seen in the direction of the central axis (A) - above the ignition gap (13) is formed.

Ignition device (1) according to claim 2, characterized in that the center electrode (9) is partially surrounded by a Isolatorfuß (23), wherein the Strömurigsleitelement (25) on the Isolatorfuß (23) is provided, and wherein the flow guide (25) preferably is formed as a radial projection (27) of a lateral surface (39) of the insulator foot (23).

Ignition device (1) according to one of claims 3 and 4, characterized

in that the flow-guiding element (25) is formed as a substantially conical projection (27) of the lateral surface (29) of the central electrode (9) and / or the lateral surface (39) of the insulator base (23).

Ignition device (1) according to claim 5, characterized in that the conical projection (27) is arranged on the central electrode (9), wherein it springs directly in the region of an axial end face (31) of the Isolatorfußes (23) and - in the axial direction extends - to the ground electrode (11) expands, with an axial end face (33) of the projection - as seen in the axial direction - a distance from the spark gap (13).

Ignition device (1) according to claim 5, characterized in that the conical projection (27) on the Isolatorfuß (23) is arranged, wherein it has its largest diameter - seen in the axial direction - at the height of an axial end face (31) of the Isolatorfußes ( 23), wherein the

Diameter - also in the axial direction - away from the ground electrode (1) pointing away.

Ignition device (1) according to one of the preceding claims 2 to 7, characterized in that the ground electrode (11) is formed as a ring electrode, which surrounds the center electrode (9) - seen in the circumferential direction -, wherein the Zündspalt (13) preferably as the center electrode (9) - in the circumferential direction is seen - encompassing annular gap is formed, and wherein the ring electrode is held by at least one spacer element (15).

9. ignition device (1) according to claim 1, characterized in that the

Igniter (1) is designed as a laser spark plug, wherein the fuel / air mixture is ignited in the ignition by at least one laser beam, and wherein the flow guide (25) is preferably arranged on a in the ignition chamber (5) provided holding element. 0. Ignition device (1) according to claim 1, characterized in that the

Ignition device (1) is designed as a corona spark plug, wherein the

Flow guide (25) is preferably arranged on a Isolatorfuß a corona electrode.

1 1. Ignition device (1) according to one of the preceding claims, characterized

characterized in that the ignition device (1) is designed as Vorkammerzündkerze, wherein the chamber wall (3) is preferably formed by a arranged on a base body of the Vorkammerzündkerze ignition cap.

12. Internal combustion engine, characterized by an ignition device (1) according to one of claims 1 to 11.

13. Internal combustion engine according to claim 12, characterized in that the

Internal combustion engine is designed as a gas engine, in particular as a lean-burn gas engine.