EP2558709A1

EP2558709A1 - Laser ignition plug with an antechamber

Info

Publication number: EP2558709A1
Application number: EP11710755A
Authority: EP
Inventors: Werner Herden; Martin Weinrotter; Pascal Woerner; Juergen Raimann
Original assignee: Robert Bosch GmbH
Current assignee: Robert Bosch GmbH
Priority date: 2010-04-13
Filing date: 2011-03-23
Publication date: 2013-02-20
Also published as: US20130199483A1; WO2011128190A1; DE102010003899A1; US8701613B2

Abstract

The invention relates to a laser ignition plug (14) having an antechamber (50), wherein the laser ignition plug (14) is designed to irradiate laser radiation into the antechamber (50), wherein the antechamber (50) comprises at least two overflow ducts (51 to 57) which realize a fluid connection between the antechamber (50) and a spatial region (204) surrounding the antechamber (50), wherein the at least two overflow ducts (51 to 57), with regard to the radial spacing (R1, R2) thereof from a longitudinal axis (60) of the antechamber (50) and/or with regard to the axial spacing (A1, A2) thereof from an end region (64), which faces toward the combustion chamber, of the antechamber (50) and/or with regard to the alignment and/or geometry thereof, are arranged asymmetrically with respect to the longitudinal axis (60) of the antechamber (50).

Description

description

title

Laser spark plug with a prechamber prior art

The invention relates to a laser spark plug according to the preamble of claim 1 and an internal combustion engine according to the independent claim. Internal combustion engines which have an air space in a combustion chamber

Ignite / fuel mixture by means of an antechamber are known. DE 10 2006 018 973 A1 describes a laser ignition in an antechamber of an internal combustion engine with a centrally arranged laser ignition device. Disclosure of the invention

The problem underlying the invention is achieved by a laser spark plug according to claim 1 and by an internal combustion engine according to the

resolved sibling claim. Advantageous developments are in

Subclaims specified.

According to the invention, the prechamber of the laser spark plug has at least two overflow channels, which are arranged asymmetrically with respect to their radial distance from a longitudinal axis of the prechamber and / or its axial distance from an end region of the prechamber facing the combustion chamber and / or its orientation and / or its geometry Longitudinal axis of the antechamber.

This takes into account the fact that laser spark plugs together with the associated pre-chamber often not exactly coaxial with a longitudinal axis of a

Cylinder or therein formed combustion chamber are arranged. Thereby arise in conventional systems adversely different

Path lengths for the emerging from the antechamber Zündfackeln in the direction of wall sections of the cylinder or combustion chamber and a

accordingly suboptimal ignition. By contrast, by means of the asymmetrical arrangement of the transfer channels according to the invention, there is one

Variety of embodiments of overflow channels available to perform a firing of the fuel even in conventional internal combustion engines with asymmetrical mounting position of the spark plug uniform.

Simplified, it can be said that by the invention

Feature combination the lengths of the ignition torches are adapted to the path lengths between the pre-chamber and the wall portions of the combustion chamber by means of a specific configuration of the overflow.

Preferably, the laser spark plug and the prechamber form a structural unit. However, it is also possible according to the invention to provide the laser spark plug and the prechamber as separate elements.

The laser spark plug according to the invention has the advantage that from its

Prechamber ignition torches can emerge so differently that, despite different path lengths between the laser spark plug and the antechamber and an opposite wall portion of the combustion chamber a

uniform burn-through of a fuel or fuel mixture is made possible. The burning time can be reduced, resulting in a better

Efficiency results. The heat losses of the combustion chamber and a tendency to knock the engine can be reduced by a faster

Burning is achieved, the tail gas has less time to ignite itself.

An embodiment provides that at least two transfer channels

unsymmetrical with respect to a radial distance to the longitudinal axis of the

Antechamber and / or in relation to an axial distance to a

combustion chamber facing end of the antechamber are arranged. Thus, properties of the ignition torches can be adapted to the combustion chamber of the target system advantageously by a respective constructive arrangement of one or more overflow channels in a wall of the prechamber. A further embodiment provides that at least two overflow channels are arranged asymmetrically with respect to their orientation with respect to the longitudinal axis of the prechamber. For example, longitudinal axes of the overflow channels or surface normals of an outer opening of the

Overflow each different angle to the longitudinal axis of the

Have antechamber. Correspondingly, the ignition torches emerging from the pre-chamber are asymmetrical with respect to the longitudinal axis of the prechamber in different spatial directions of the combustion chamber. In accordance with this, unsymmetrically directed ignition torches can be generated and thus the laser spark plug or the pre-chamber can be connected to a present asymmetry of the

Combustion chamber or an installation position of the laser spark plug or the antechamber are advantageously adapted.

A further embodiment provides that at least two transfer channels with respect to their geometry asymmetrically with respect to the longitudinal axis of the

Prechamber arranged and / or formed. So that can

Overflow channels are optimized, for example, with respect to their cross-sectional shape or their diameter or their cross-sectional area or a ratio of their axial length and their cross-sectional area. In general, a pulse of a firing torch and, correspondingly, an achievable torch length with a larger cross-sectional area of the transfer port increases. The maximum achievable torch length also depends on a pressure and a temperature in the

From combustion chamber, as well as from a fuel-air mixture. This relationship can preferably be determined from measured variables or by calculations by means of a combustion process analysis and / or simulations.

Furthermore, the invention proposes that a cross section of at least one overflow channel along a longitudinal axis of the overflow channel

having different cross-sectional areas and / or cross-sectional shapes. Thus, further variants are presented according to set a length of a Zündfackel invention and to improve the operation of the laser spark plug. For example, the cross-sectional shape of one or more transfer passages may be at least partially circular, elliptical or rectangular. Likewise, the cross-sectional areas of the overflow channels and / or the cross-sectional shapes along the longitudinal axis of the overflow channel can vary almost as desired. If an overflow channel is not straight Having longitudinal axis, can be understood by the "longitudinal axis" a spatially curved line, which by respective focal points of

Cross-sectional surfaces runs. A further embodiment of the invention provides that at least one

Overflow essentially has the geometry of a cone. This is advantageous in a simple way given a way to influence the manner of a nozzle, a resulting shape of the Zündfackeln. The laser spark plug can be used more versatile if the overflow channels at least partially have mutually different geometries. This makes it particularly easy to tune the shape of the Zündfackeln even better.

Sizing of the overflow channels is particularly easy to achieve if a second cross-sectional area Qn of at least one second

Overflow channel is determined in dependence on a first

Cross-sectional area Q1 of a first transfer port and a second

Path length Wn starting from the antechamber along a longitudinal axis of the second overflow channel to a second wall portion of a

Combustion chamber wall, the second overflow in installation position of the

Laser spark plug in an internal combustion engine opposite, and a first path length W1, starting from the antechamber along a longitudinal axis of the first transfer port to a first wall portion of the

Combustion chamber wall, the first overflow in installation position of the

Laser spark plug in the internal combustion engine opposite. Thus, several or all overflow channels of the prechamber can be made dependent on one another according to available mechanical parameters and thus be better coordinated with each other. The path lengths W1 and Wn are preferably determined starting from an outer opening of the overflow channel, so that a wall thickness of the pre-chamber is irrelevant for this purpose.

In particular, the invention proposes that a quotient of the second cross-sectional area Qn and the first cross-sectional area Q1 is substantially proportional to a quotient of the second path length Wn and the first path length W1. This can advantageously be a formula for calculating the Cross-sectional areas of the transfer channels are given, wherein any one of the arranged in the pre-chamber overflow channels with its cross-sectional area Q1 and its path length W1 is a reference for calculating the remaining transfer channels.

The formula is thus: Qn = Q1 * (Wn / W1), where Qn and Wn are each the values of any of the remainder

Represent overflow channels.

Furthermore, it is proposed that the second cross-sectional area Qn depends on the first cross-sectional area Q1, the first and second path length W1, Wn, and on a number k, where k> = 0, according to the equation Qn = Q1 ^* (Wn / W1) ^A k , The number k represents an exponent. So the equation is in a different notation:

Wn

Qn = Q

Thus, advantageously, a proportional (k = 1), progressive (k> 1) or degressive (0 <k <1) relationship between the quotient of the second and the first cross-sectional area Qn, Q1 on the one hand and the quotient of the second and the first Path length Wn, W1 are produced on the other hand.

Furthermore, it is proposed that in the case of a conical geometry of an overflow channel, the cone opens to an outer surface of the antechamber. This is particularly useful if an external opening of the

Overflow along the longitudinal axis of the overflow - in installation position of the laser spark plug in the internal combustion engine - closer to a wall surface of the combustion chamber (combustion chamber wall) is arranged, as this is the case on average of the other transfer channels. Thus, the emerging from the antechamber ignition torch can be widened, wherein it loses its effect in their exit direction.

Conversely, it is proposed that the cone becomes one

Inner surface of the antechamber opens. This is particularly useful when an outer opening of the overflow along the longitudinal axis of the Uberströmkanals - in installation position of the laser spark plug in the internal combustion engine - is further away from a wall surface of the combustion chamber (combustion chamber wall), as this is the case on average of the other transfer channels. Thus, the emerging from the antechamber ignition torch can be bundled so to speak, where it increases in their discharge direction to effect, thus increasing their length in the direction of propagation.

A further embodiment of the laser spark plug provides that a

Cross-sectional area of at least one overflow channel up to 10

Square millimeters. As a rough guideline for overflow channels with a circular cross-section it follows that up to a channel diameter of approximately 3 millimeters, the torch length of a passing ignition torch increases. As a result, a diameter range of the overflow channels up to about 3 millimeters is particularly useful. This is roughly equivalent to one

Cross sectional area of 7 square millimeters. In particular, depending on a specific design of an internal combustion engine, a diameter of the overflow channels of approximately 1.2 mm to approximately 2 mm may be particularly suitable.

Furthermore, it is provided that a ratio of an area of an inner opening of the overflow channel to a surface of an outer opening of the overflow channel is between 1:10 and 10: 1. For overflow channels with circular

Cross-section shows that a ratio of the openings is correspondingly between about 1: 3.16 and about 3.16: 1. This is a particularly suitable area for carrying overflow channels with different areas of the inner opening and the outer opening.

In a further embodiment, the invention also takes into account that a longitudinal section of at least one overflow channel can at least partially have parabolic or hyperbolic shapes. Such geometries can be combined particularly well with conical geometries, that is, in each case fluidically meaningful transitions between these geometries can be carried out for an overflow channel.

In a further variant of the invention, it is provided that the prechamber several arranged radially in a circumferential wall in an antechamber wall Overflow has channels which have mutually different cross-sectional areas and / or geometries. This allows a particularly versatile embodiment of the laser spark plug according to the invention. In particular, overflow channels can be arranged or aligned in all suitable spatial directions of the combustion chamber, wherein in addition, by different cross-sectional areas or geometries, the shapes of the ignition torches can be performed individually.

It is understood that the described embodiments can also be advantageously combined with each other.

The laser spark plug according to the invention may alternatively have an antechamber which comprises only a single overflow channel. Analogously, the invention therefore provides that the single overflow channel can be aligned in different directions of the combustion chamber, wherein it is not aligned in particular coaxially to the longitudinal axis of the prechamber. This can be achieved, inter alia, that any dirt particles or oil drops only conditionally from the main combustion chamber in the antechamber, and there in particular a combustion chamber window, get. Preferably, the only overflow is aligned so that it - in installation position of the laser spark plug in the

Internal combustion engine - in the direction of a comparatively distant

Wall portion of the combustion chamber has. In addition, its geometry can be designed according to the embodiments of the above-described at least two overflow channels. For example, the cross-sectional area and / or the cross-sectional shape along the longitudinal axis of the overflow be different to fill the combustion chamber as evenly as possible with the emerging from the single overflow port ignition torch, the respective path lengths between the outer opening of the overflow and wall sections of the combustion chamber mutatis mutandis to those described above arrangements

be taken into account.

An important embodiment of the invention relates to an internal combustion engine having at least one laser spark plug, wherein the overflow of the

Antechamber with respect to its radial distance from a longitudinal axis of the prechamber and / or its axial distance from a combustion chamber facing

End region of the pre-chamber and / or its orientation and / or its geometry are arranged so that reach out of the overflow ducts igniting flares of the flamed fuel located in the main propagation direction of the respective Zündfackeln wall sections of a combustion chamber substantially simultaneously. In particular, this relates to the flame fronts emanating from the ignition flares, which are preferably to reach the wall sections of the combustion chamber at the same time. Due to currents in the

Combustion chamber and as a result of an existing temperature distribution and / or a possibly inhomogeneous fuel-air mixture reach the

Flame fronts often even in an ideally symmetrical

Combustor geometry the wall sections at different times. Therefore, according to the invention in the design of the prechamber with respect to the position, the number, the shape and the orientation of the overflow not only a present combustion chamber geometry, but also the flows and the propagation of the flame fronts are taken into account. This can be done for example by means of a three-dimensional computer simulation. In this way, internal combustion engines can be ignited more uniformly by means of the laser spark plug according to the invention by a fuel ignited in a cylinder or its combustion chamber experiences a more uniform and especially faster burn through, whereby the efficiency of

Internal combustion engine can be optimized. Likewise, heat losses in the cylinder wall or a tendency to knock the internal combustion engine can be reduced.

It is understood that the internal combustion engine according to the invention can be operated either with liquid or gaseous fuels, and that the

Internal combustion engine either mainly for mobile use

(Motor vehicle) or a stationary use can be provided, for example, as a stationary large gas engine. Features important to the invention can be found further in the following

Drawings, the features being both unique and in

different combinations may be important for the invention, without being explicitly referred to again.

Hereinafter, exemplary embodiments of the invention will be explained with reference to the drawings. In the drawing show: FIG. 1 shows a laser-based ignition system for an internal combustion engine of a motor vehicle with a laser spark plug according to the invention,

FIG. 2 shows a combustion chamber-facing end section of another

Embodiment of the laser spark plug according to the invention,

FIG. 3 shows a combustion chamber-facing end section of another

Embodiment of the invention in an enlarged view;

FIG. 4 shows a combustion chamber-facing end section of another

Embodiment of the invention with a variety of embodiments of overflow channels; and

Figure 5 shows a cross section through an antechamber and a wall of a

Combustion chamber of a further embodiment of the invention.

The same reference numerals are used for functionally equivalent elements and sizes in all figures, even in different embodiments.

FIG. 1 shows a laser-based ignition system for an internal combustion engine of a motor vehicle. The ignition system includes a pump light source 10 having, for example, a semiconductor diode laser for generating laser radiation for optically pumping a laser device. The of the

Pumplichtquelle 10 generated laser radiation is transmitted via an optical fiber device 12 to a laser in a spark plug 14 integrated laser device 16. The laser device 16 can be, for example, a laser-active solid with a passive Q-switching (not shown), with which laser radiation or laser pulses 20 of high power can be generated in a manner known per se. The laser spark plug 14 protrudes in its installed position in the internal combustion engine partly into a combustion chamber 200 formed in a cylinder 201 or into a space region 204 formed therein and has four overflow channels 51, 52, 53 and 54 on its section protruding into the space region 204. These are designed, for example, as holes with different orientations and diameters. In the figure 1, the laser spark plug 14 is designed so that it forms an antechamber 50 with its projecting into the combustion chamber 200 in the section. The pre-chamber 50 is thus present no separate item, but is in the

Laser spark plug 14 integrated. It is understood that the number of

Transfer channels do not have to be four as in the present case, but can be almost arbitrary, as will be shown in the following figures.

The laser device 16 has focusing optics 18 for focusing the laser pulses 20 on an ignition point ZP lying in the prechamber 50 of the laser spark plug 14. The ignition point ZP is preferably in the Innenren of

Prechamber 50, i. not directly in the area of an inner surface of the

Prechamber. However, the ignition point ZP can also be relatively close to the prechamber inner wall or, if appropriate, also directly thereon. One

Combustion chamber window 22 is disposed between the focusing optics 18 and the prechamber 50.

It can be seen from FIG. 1 that the laser spark plug 14 in the present case is not arranged coaxially along a longitudinal axis 202 of the cylinder 201 or the combustion chamber 200, and is therefore installed asymmetrically in the combustion chamber 200. The section 204a of the combustion chamber 200 located on the left of the prechamber 50 in the drawing of FIG. 1 is thus smaller than the section 204b of the combustion chamber 200 on the right of the prechamber 50. The overflow channels 53 and 54 therefore have a larger cross section than the cross section

Überströmkanäle 51 and 52. Thus, the emerging from the transfer ports 53 and 54 Zündfackeln are longer and can therefore to a

contribute more uniform burnout of the located in the combustion chamber 200 fuel.

Deviating from this, a further embodiment of the laser spark plug 14 according to the invention provides that the laser spark plug 14 and the pre-chamber 50 is arranged substantially coaxially to the longitudinal axis 202 of the cylinder 201 and the combustion chamber 200, however, a cavity of the piston facing the combustion chamber 200 asymmetrically in With respect to the longitudinal axis 202 is formed. As a result of the asymmetrical piston recess, this results in a virtual asymmetry of the combustion chamber with respect to the prechamber 50.

Accordingly, the above descriptions may apply mutatis mutandis to this Embodiment transferred. However, this is not shown in the drawing of Figure 1.

Yet another embodiment of the invention

Laser spark plug 14 provides that the pre-chamber 50 is approximately flush with a

Wall section of the combustion chamber 200 closes. The overflow channels are arranged distributed in this embodiment on an end face of the prechamber 50. However, this is not shown in FIG. FIG. 2 shows a further embodiment of a device according to the invention

Laser spark plug 14, which is arranged on a portion of a cylinder head 203, in a relation to the Figure 1 enlarged view. The laser spark plug 14 and the surrounding combustion chamber 200 are only partially shown. The transfer ports 51, 52, 53 and 54 are present as

Drilled holes or openings, the orientations by in the

Drawing illustrated longitudinal axes 51 a, 52 a, 53 a, and 54 a are described. The laser spark plug 14 and also the pre-chamber 50 formed on the laser spark plug 14 and an antechamber wall 62 are substantially

executed radially symmetrically about a longitudinal axis 60.

It can be seen that the overflow channels 51 and 54 have approximately the same cross sections, whereas the cross section of the overflow channel 53 is larger. The overflow channel 52 is designed as a conical opening which opens to the interior of the prechamber 50.

FIG. 3 shows an enlarged view of an end region 64 of the prechamber 50 of the laser spark plug 14 in a similar manner to FIG

Execution. In the present case, the pre-chamber 50 has two overflow channels 51 and 52, which are each designed conical. The overflow channel 51 opens outward in the direction of the combustion chamber 200, whereas the overflow channel

52 opens inwardly toward the prechamber 50. An outer opening 59a and an inner opening 59b are designated by the example of the overflow channel 52. Furthermore, an outer surface 62a and an inner surface 62b of the prechamber wall 62 are described by reference numerals. The transfer passage 51 is oriented toward a comparatively close wall portion 200a of the cylinder 201 and the combustion chamber 200 along a path length W1, and the transfer passage 52 is oriented toward a comparatively remote wall portion 200b of the cylinder 201 and the combustion chamber 200, respectively, along a path length Wn , Out of drawing

For reasons, the path lengths W1 and Wn are not shown to scale in FIG. Likewise, the wall portions 200a and 200b are shown only schematically, it being understood that the wall portions 200a and 200b need not necessarily have the arbitrarily chosen orientation in the drawing.

FIG. 4 shows a selection of variants of overflow channels. The

Laser spark plug 14 and the cylinder head 203 are shown only partially in the drawing. The illustrated arrangement of the overflow channels 51, 52, 53, 54, 55, 56 and 57 together with their longitudinal axes 51 a, 52 a, 53 a, 54 a, 55 a, 56 a and 57 a represents a variety of possibilities, wherein the drawn in the figure 4 combinations are only exemplary and need not necessarily be useful in the arrangement shown.

In the present case, all seven transfer channels are designed as bores. The overflow channel 52 has a cross-sectional area Q1 and the

Overflow channels 53, 54, 56 and 57 have partly deviating cross-sectional areas Qn. The overflow channel 52 serves, for example, as a reference for the dimensioning of the cross sections Qn of the overflow channels 53, 54, 56 and 57, corresponding to one of the following formulas:

Qn = Q1 * (Wn / W1), or

Qn = Q1 * (Wn / W1) ^A k, with path lengths W1 and Wn (not shown in FIG

Longitudinal axes 52a, 53a, 54a, 56a and 57a between the overflow channels 52, 53, 54, 56 and 57 and (not shown) wall portions of the cylinder 201 and the combustion chamber 200. Here, the number k is an exponent (k> = 0) , In the present case, the designations Q1, Qn, W1 and Wn are used equally as formula letters as well as reference numerals. The above formulas are a particularly suitable method for measuring the cross-sectional areas of the overflow channels. Deviating from this, of course, other values for the cross-sectional areas may be useful.

Furthermore, the overflow channels 51 and 52 have a different radial distance R1 to the longitudinal axis 60 of the laser spark plug 14 than the

Overflow 54, which has a radial distance R2. In addition, the overflow 52 has a different axial distance A1 to the

End portion 64 of the laser spark plug 14 as the overflow channel 57, which has an axial distance A2. Similarly, the overflow channel 53 is aligned with the longitudinal axis 60 at an angle Alfa, and the overflow channel 54 with a slightly smaller angle beta. The transfer passages 51 and 55 are tapered, similar to the example shown in FIG.

FIG. 5 shows an axial cross section through an antechamber 50 and through a wall of the cylinder 201. The sectional plane is selected such that four overflow channels 51 to 54 are cut axially in the middle and thus visible. In the figure 5, the associated four longitudinal axes 51 a to 54 a are shown in addition.

A representation comparable to that shown in FIG. 5 also results when using a piston trough of asymmetrical design with respect to the longitudinal axis 202. However, this is not explained in detail here.

It can be seen that the overflow channels 51 to 54 are not distributed uniformly along a circumference of the pre-chamber wall 62. The overflow channel 54 is aligned with its outer opening 59 a on a portion 204 a of the combustion chamber 200, and the transfer ports 51 to 53 are aligned with its outer opening 59 a on a portion 204 b of the combustion chamber 200. Reference numeral 59a is explained in more detail in FIG. In this case, the uneven distribution of the transfer passages 51 to 54 can improve the burn-through of the fuel in the combustion chamber 200 by essentially igniting the smaller portion 204a from one transfer passage 54 and the larger portion 204b from substantially three transfer passages 51 to 53. It can also be concluded from this that a cross-sectional area of the overflow channel 54 is to be dimensioned smaller than the respective ones

Cross-sectional areas of the overflow channels 51, 52 and 53, to limit a length of a propagating in the direction of the longitudinal axis 54a Zündfackel.

Thus, in addition to those presented in Figures 1 to 4

unbalanced arrangements of the overflow 51 to 57 in terms of their radial and / or axial distance, their orientation and their geometry a further degree of freedom by an asymmetrical arrangement of the

Overflow channels 51 to 57 given in the axial sectional plane. It goes without saying that the examples presented in FIGS. 1 to 5 can also advantageously be combined with one another.

As can be seen from FIGS. 1 to 5, the statements presented therein presuppose that the laser spark plug 14 must be installed in the combustion chamber 200 or cylinder 201 in a directed manner, if it is to act optimally.

Claims

claims

1 . Laser spark plug (14) having an antechamber (50), wherein the laser spark plug (14) is adapted to irradiate laser radiation (20) in the prechamber (50), wherein the prechamber (50) comprises at least two overflow channels (51 to 57), which realize a fluid connection between the prechamber (50) and a space area (204) surrounding the prechamber (50), characterized in that the at least two

Overflow channels (51 to 57) with respect to their radial distance (R1, R2) from a longitudinal axis (60) of the prechamber (50) and / or its axial distance (A1, A2) from a combustion chamber facing end portion (64) of the prechamber (50) and / or their orientation and / or their geometry are asymmetrically arranged and / or formed with respect to the longitudinal axis (60) of the pre-chamber (50).

2. laser spark plug (14) according to claim 1, characterized in that a cross section of at least one overflow channel (51 to 57) along a longitudinal axis (51 a to 57 a) of the overflow channel (51 to 57) different cross-sectional areas (Q1, Qn) and / or Has cross-sectional shapes.

3. laser spark plug (14) according to claim 1 or 2, characterized in that at least one overflow channel (51, 55) substantially the

Has geometry of a cone.

4. laser spark plug (14) according to at least one of the preceding claims, characterized in that the overflow channels at least partially have mutually different geometries.

5. Laser spark plug (14) according to at least one of the preceding claims, characterized in that a second cross-sectional area (Qn) of at least one second overflow channel (51 to 57) is determined as a function of: - A first cross-sectional area (Q1) of a first Uberströmkanals (51 to 57) and

- A second path length (Wn) starting from the pre-chamber (50) along a longitudinal axis (51 a to 57 a) of the second overflow channel (51 to 57) to a second wall portion (200 a, 200 b) of a combustion chamber wall, the second overflow channel (51 to 57) in installation position of the laser spark plug (14) in an internal combustion engine opposite, and

- A first path length (W1) starting from the pre-chamber (50) along a longitudinal axis of the first transfer port (51 to 57) to a first wall portion (200a, 200b) of the combustion chamber wall, the first overflow channel (51 to 57) in the installed position of Laser spark plug (14) in the internal combustion engine is opposite.

Laser spark plug (14) according to claim 5, characterized in that a quotient of the second cross-sectional area (Qn) and the first

Cross sectional area (Q1) is substantially proportional to one

Quotients of the second path length (Wn) and the first path length (W1).

Laser spark plug (14) according to one of claims 5 to 6, characterized

characterized in that the second cross-sectional area (Qn) depends on the first cross-sectional area (Q1), the first and second path lengths (W1, Wn), and a number k, according to the equation Qn = Q1 ^* (Wn / W1) ^A k k> = 0th

Laser spark plug (14) according to claim 3, characterized in that the cone opens towards an outer surface (62a) of the prechamber (50).

Laser spark plug (14) according to claim 3, characterized in that the cone opens towards an inner surface (62b) of the prechamber (50).

Laser spark plug (14) according to at least one of the preceding claims, characterized in that a cross-sectional area (Q1, Qn) of at least one overflow channel is up to 10 square millimeters. Laser spark plug (14) according to at least one of the preceding claims, characterized in that a ratio of a surface of a Inner opening (59b) of the overflow channel (51 to 57) to a surface of an outer opening (59a) of the overflow channel (51 to 57) is between 1:10 and 10: 1.

Laser spark plug (14) according to at least one of the preceding claims, characterized in that a longitudinal section of at least one

Overflow channel (51 to 57) at least partially parabolic or hyperbolic shape has.

Laser spark plug (14) according to at least one of the preceding claims, characterized in that the prechamber (50) has a plurality of in a pre-chamber wall (62) radially circumferentially arranged overflow channels (51 to 57), which mutually different cross-sectional areas (Q1, Qn) and / or Have geometries.

Internal combustion engine having at least one laser spark plug (14) according to at least one of the preceding claims, characterized in that the overflow channels (51 to 57) of the prechamber (50) with respect to their radial distance (R1, R2) from a longitudinal axis (60) of the prechamber (50 ) and / or its axial distance (A1, A2) from one

combustion chamber-facing end region (64) of the antechamber (50) and / or its orientation and / or its geometry are arranged such that wall sections (200a, 200b) which emerge from the overflow channels (51 to 57) emit ignition torches of the ignited fuel in the main propagation direction of the relevant ignition torches. reach a combustion chamber (200) substantially simultaneously.