Prechamber spark plug for a combustion chamber of an internal combustion engine, internal combustion engine and motor vehicle

Abstract

Prechamber spark plug (10) for a combustion chamber of an internal combustion engine, with a prechamber (12) having several openings (16, B1, B2), which can be fluidically connected to the combustion chamber via the openings (16, B1, B2), through which a fuel-air mixture can be introduced from the combustion chamber into the prechamber (12), wherein each opening (16, B1, B2) has a respective flow cross-section through which the fuel-air mixture can flow, wherein, with respect to an imaginary first plane (E1) extending in the longitudinal direction (24) of the prechamber (12) and dividing the prechamber (12) into two equal halves (H1, H2), several first openings (16, B1, B2) are arranged in one of the halves (H1, H2) and several second openings (16, B1, B2) are arranged in the second half (H2), wherein the first openings (B1) in the circumferential direction (28) of the prechamber (12) by a respective first angle (β1) from an imaginary,in the longitudinal direction (24) of the pre-chamber (12) and extending perpendicularly to the first plane (E1), the second openings (B2) are spaced apart, wherein the second openings (B2) are spaced apart in the circumferential direction (28) of the pre-chamber (12) by a respective second angle (β2) from the second plane (E2), wherein the mean value of the first angles (β1) is smaller than the mean value of the second angles (β2), and wherein the openings (16) are rotationally asymmetric about an imaginary axis (A) extending in the longitudinal direction (24) of the pre-chamber (12), in which the planes (E1, E2) intersect, and the pre-chamber (12) is rotationally symmetric with respect to the axis (A), characterized in that: , - the openings (16) are designed as bores; and / or - the flow cross-sections of at least two of the openings (16) differ from each other with regard to their shape.

Description

[0001] The invention relates to a prechamber spark plug for a combustion chamber of an internal combustion engine, in particular of a motor vehicle, according to the preamble of patent claim 1. Furthermore, the invention relates to an internal combustion engine for a motor vehicle according to the preamble of patent claim 7. The invention also relates to a motor vehicle, in particular a motor vehicle.

[0002] EP 2 700 796 A1 discloses a pre-combustion chamber tip of a pre-combustion chamber arrangement of an internal combustion engine. Furthermore, a pre-combustion chamber is known from US 2013 / 0 055 986 A1. Furthermore, a pre-chamber spark plug for an internal combustion engine is known from DE 10 2018 007 093 A1. JP 2012-211 594 A discloses a pre-chamber spark plug. An internal combustion engine is known from DE 10 2018 117 726 A1.

[0003] The object of the present invention is to provide a pre-chamber spark plug for a combustion chamber of an internal combustion engine, an internal combustion engine with at least one such pre-chamber spark plug and a motor vehicle, so that a particularly advantageous operation of the internal combustion engine can be realized.

[0004] This object is achieved by a pre-chamber spark plug having the features of patent claim 1, by an internal combustion engine having the features of patent claim 7, and by a motor vehicle having the features of patent claim 8. Advantageous embodiments with expedient further developments of the invention are specified in the remaining claims.

[0005] A first aspect of the invention relates to a pre-chamber spark plug for a combustion chamber of an internal combustion engine, also referred to as an internal combustion engine, in particular for a motor vehicle. The pre-chamber spark plug has a pre-chamber with a plurality of openings, for example designed as through-openings, via which the pre-chamber is or can be fluidically connected to the combustion chamber. In particular, the opening can run straight or rectilinearly, in particular over its entire extent. A fuel-air mixture, also simply referred to as a mixture, can be introduced from the combustion chamber into the pre-chamber via the respective opening. For example, at least one ignition spark can be generated in the pre-chamber. For this purpose, the pre-chamber spark plug comprises, for example, at least one electrode device which is at least partially arranged in the pre-chamber.The electrode device can generate the aforementioned ignition spark in the prechamber. The ignition spark can ignite or ignite the fuel-air mixture, which has flowed into the prechamber through the openings, in the prechamber and subsequently combust, so that, for example, flames or burning flares resulting from the ignition and combustion of the mixture can flow out of the prechamber through the openings and enter or enter the combustion chamber. As a result, the mixture remaining in the combustion chamber is ignited and combusted.

[0006] The respective opening has a respective flow cross-section through which the mixture or the respective flare can flow. The respective flow cross-section is thus, for example, an area through which the mixture can flow, or has an area or surface area and through which the mixture can flow. In particular, the flow cross-section is understood to be the respective smallest or least significant flow cross-section through which the mixture can flow at the respective opening.

[0007] In order to be able to realize a particularly advantageous operation of the internal combustion engine, it is provided according to the invention that, with respect to an imaginary or virtual first plane running in the longitudinal direction of the prechamber, that is to say parallel to the longitudinal direction of the prechamber and thus of the prechamber spark plug as a whole and dividing the prechamber into two equal halves, a plurality of first of the openings and thus, for example, at least two or at least three first of the openings are arranged in a first of the halves, and a plurality of second of the openings, that is to say at least two or preferably at least three second of the openings are arranged in the second half.The first openings arranged in the first half are spaced from an imaginary second plane by a respective first angle, for example, located in the first half, in the circumferential direction of the pre-chamber, which runs in particular around the longitudinal direction of the pre-chamber, wherein the imaginary or virtual second plane runs in the longitudinal direction of the pre-chamber, i.e. parallel to the longitudinal direction of the pre-chamber, and extends perpendicular to the first plane. The second openings are spaced from the second plane by a respective second angle, for example, located in the second half, in the circumferential direction of the pre-chamber. Furthermore, the invention provides that the mean value of the first angles is smaller than the mean value of the second angles. In particular, the mean value is to be understood as the arithmetic mean.Thus, for example, the first mean is obtained by dividing the sum of the or all first angles, in particular those in the first half, by the number of or all first angles. Accordingly, for example, the second mean is obtained by dividing the sum of the or all second angles, in particular those in the second half, by the number of or all second angles.

[0008] To achieve particularly advantageous operation, it is also provided that the planes intersect in an imaginary axis running in the longitudinal direction of the prechamber and thus of the prechamber spark plug as a whole. The openings are rotationally asymmetric around the axis, in which the planes are designed. In other words, the axis runs parallel to the longitudinal direction of the prechamber. The aforementioned axis is, for example, a longitudinal central axis of the prechamber, also referred to as the main axis, which can be rotationally symmetrical with respect to the axis, or with respect to the longitudinal central axis, also referred to as the longitudinal axis.

[0009] Furthermore, the invention provides that the openings are designed to be rotationally asymmetrical about the imaginary axis running in the plane. This is to be understood, for example, in particular that the openings are arranged asymmetrically, i.e., unevenly, around the axis and thus in the circumferential direction of the prechamber or prechamber spark plug running around the axis. Alternatively or additionally, the feature that the openings are designed or constructed to be rotationally asymmetrical around the axis can be understood to mean that the or all of the openings follow one another unevenly or randomly around the axis, i.e., do not follow one another in a regular sequence, particularly with regard to the different angles.In other words, the rotationally asymmetric design can be understood to mean that the or all angles around the axis follow one another unevenly or in a disordered manner, i.e. not in a regular sequence.

[0010] Furthermore, it is conceivable that at least two of the openings differ from one another in their geometry, in particular in the geometry of their respective flow cross-section, and in doing so have a rotationally asymmetric sequence, in particular around the axis. This means in particular that the flow cross-sections of these at least two openings differ from one another, in particular with regard to their shape and / or size, i.e. area or surface area, wherein the at least two openings or preferably all openings have a rotationally asymmetric sequence around the axis. This means in particular that the at least two openings or preferably all openings follow one another around the axis in an irregular or disordered manner, i.e. not in a regular sequence.

[0011] Due to this rotationally asymmetrical arrangement or design of the openings, the openings are designed to cause a tumble-like flow, also referred to as a roller flow, roller flow, or tumble flow, of the fuel-air mixture flowing into the prechamber via the openings. In other words, during fired operation of the internal combustion engine, the openings, for example through their arrangement and / or their number and / or their geometry, cause a tumble-like flow of the fuel-air mixture, also referred to simply as the mixture, flowing through the openings and thereby flowing from the combustion chamber into the prechamber, which thus has a tumble-like flow, or the tumble-like flow, at least in the prechamber.In other words, the openings, which are designed as through-openings, for example, impose an at least substantially tumble-shaped and thus cylindrical flow, also referred to as tumble flow, on the mixture flowing through the openings and thereby from the combustion chamber, also referred to as the main combustion chamber, into the pre-chamber, so that particularly advantageous operation of the pre-chamber spark plug and thus of the internal combustion engine as a whole can be achieved. The tumble-shaped flow is a flow which is at least substantially cylindrical in at least or exactly one cylindrical plane. This cylindrical plane runs, for example, in the longitudinal direction of the pre-chamber spark plug and can be the first plane or the second plane, or the cylindrical plane is a third plane which runs obliquely to the first plane and obliquely to the second plane.In particular, the tumble-shaped flow runs in a cylindrical manner around a roller axis that is perpendicular to the roller plane and thus is a plane normal to the roller plane. For example, the roller axis runs in the first plane.

[0012] In contrast to a flow that is rotationally symmetrical, in particular with respect to the axis, which extends, for example, in a helical or annular manner around the main axis or around the longitudinal axis of the prechamber, the tumble-shaped flow is a roller-shaped flow, also referred to as a roller flow, which, for example, extends at least partially in the roller plane or runs in the roller plane in which, for example, the axis, in particular the main axis, lies or runs. The aforementioned, conventionally provided rotationally symmetrical flow can result in particular from an arrangement and design of the openings that is rotationally symmetrical, in particular with respect to the axis, although according to the invention, a rotationally asymmetrical arrangement or design of the openings with respect to the axis is now provided.

[0013] The tumble flow has a positive effect on combustion in the prechamber in several ways, allowing a particularly large working range for the prechamber spark plug or in the prechamber to be achieved. Firstly, there is better purging of residual gas in the region of a spark plug gap, which is formed or delimited, for example, by respective electrodes, in particular by respective ends of the electrodes. The electrodes are, for example, electrodes of the aforementioned electrode device. The free ends, in particular, are arranged, for example, in the prechamber. In the spark plug gap, the ignition spark for igniting the mixture in the prechamber can be generated, for example by means of the electrodes. The better purging ensures more stable ignition.Compared to conventional spark plugs, this results in more favorable convection of the initial flame core toward the openings, also known as nozzles or nozzles. The improved purging and more favorable convection allow for a more combustion-friendly design of the respective electrode of the prechamber spark plug, particularly with regard to a lower penetration depth of the electrode, for example, designed as a ground electrode. This results in a smaller surface area, which in turn results in lower wall heat losses. This can reduce the pre-ignition tendency compared to conventional prechamber spark plugs.

[0014] In conventional pre-chamber spark plugs, the openings, particularly due to their rotationally symmetrical arrangement, ensure an at least essentially rotationally symmetric flow of the mixture flowing through the openings and thus from the combustion chamber into the pre-chamber. The disadvantage here is that the initial flame core is not convected or is convected away from the openings, also known as pre-chamber nozzles. To ensure sufficiently low residual gas contents in the area of ​​the spark plug gap with conventional pre-chamber spark plugs, a long electrode that extends deep into the pre-chamber is usually required. This results in a jagged surface in the pre-chamber and a large damage volume. The aforementioned problems and disadvantages can now be avoided with the pre-chamber spark plug according to the invention.

[0015] Combustion in the prechamber is stabilized and improved by the tumble flow. This increases the working area of ​​the prechamber spark plug, allowing for more stable ignition at idle and a lower risk of pre-ignition at full load. Furthermore, the improved combustion results in a greater pressure increase in the prechamber and consequently a deeper flare penetration depth into the combustion chamber. This also improves combustion in the combustion chamber, also known as the main combustion chamber. Flare penetration depth refers in particular to the distance, depth, or path the flares travel into the prechamber or combustion chamber. The respective flare results from the mixture being ignited and subsequently burned in the prechamber.

[0016] Prechamber spark plugs can traditionally be differentiated according to the flow structure in the prechamber. In particular, according to the state of the art, a distinction can be made between structureless (chaotic) flow patterns in the prechamber and rotationally symmetric flow patterns. The flow structure is determined in particular by the arrangement of the openings and by the design of the openings. For rotationally symmetric flow structures, according to the state of the art, the arrangement of the openings is rotationally symmetric about the aforementioned axis, which is, for example, the main axis of the prechamber.

[0017] According to the invention, however, a rotationally asymmetric design and arrangement of the openings is provided so that a particularly advantageous operation can be realized.

[0018] Each opening is designed as a bore. Alternatively or additionally, the flow cross-sections of at least two of the openings differ from one another in terms of their shape. The prechamber is designed to be rotationally symmetrical with respect to the axis.

[0019] It has proven particularly advantageous if the openings are arranged along an imaginary circle whose center lies on the axis, with the first plane dividing the circle into two equally sized imaginary halves. For example, a first of the halves is arranged, in particular entirely, in the first half of the prechamber, while the second half, in particular entirely, is arranged or extends in the second half of the prechamber. The respective half of the prechamber is also referred to as the prechamber half or chamber half.

[0020] A further embodiment is characterized in that one or the number of openings arranged in the first half is larger than one or the number of openings arranged in the second half.

[0021] In a further, particularly advantageous embodiment of the invention, the respective opening has the aforementioned respective flow cross-section. It is preferably provided that the sum of the flow cross-sections of the openings arranged in the first half is greater than the sum of the flow cross-sections of the openings arranged in the second half. The feature that the openings are arranged along the imaginary circle can be understood in particular to mean that respective centers or geometric centers of gravity, in particular area centers of gravity, of the openings or of the flow cross-sections are arranged on the imaginary circle and along the circle, in particular consecutively.

[0022] Since, for example, the sum of the flow cross sections of the openings arranged in the first half or on the first half of the circle is greater than the sum of the flow cross sections of the openings arranged in the second half or on the second half of the circle, the openings can impart a particularly advantageous tumble-shaped flow to the mixture flowing through the openings and thereby flowing into the prechamber.

[0023] A further embodiment is characterized in that the or all flow cross-sections of the openings arranged in the first half are larger than the or all flow cross-sections of the openings arranged in the second half. This ensures particularly advantageous flow conditions and thus particularly advantageous operation.

[0024] In a further embodiment of the invention, the mean value of the flow cross-sections of the first openings arranged in the first half is greater than the mean value of the flow cross-sections of the second openings arranged in the second half. These respective mean values ​​are also preferably understood to be the arithmetic mean.

[0025] For example, the respective openings and thus the respective flow cross-sections, in particular all flow cross-sections, are circular, so that the respective flow cross-section has a respective diameter. It is preferably provided that the or all diameters of the first openings arranged in the first half are larger than the or all diameters of the second openings arranged in the second half.

[0026] A second aspect of the invention relates to an internal combustion engine, preferably designed as a reciprocating piston engine, for a motor vehicle, which can preferably be designed as a motor vehicle and very preferably as a passenger car or as a commercial vehicle. The internal combustion engine has at least one combustion chamber. The combustion chamber is, for example, partially delimited by a cylinder and by a piston of the internal combustion engine arranged so as to be translationally movable in the cylinder, wherein the cylinder is formed or delimited, for example, by an engine housing of the internal combustion engine, which is designed in particular as a crankcase or cylinder crankcase. In addition, the combustion chamber is, for example, partially delimited by a combustion chamber roof, which is formed, for example, by a cylinder head designed separately from the engine housing and connected to the engine housing.The internal combustion engine also has at least one pre-chamber spark plug assigned to the combustion chamber, which is, for example, at least partially arranged in the combustion chamber. The pre-chamber spark plug comprises a pre-chamber with a plurality of openings via which the pre-chamber is fluidly connected to the combustion chamber, also referred to as the main combustion chamber. A fuel-air mixture, also simply referred to as a mixture, can be introduced or flow into the pre-chamber from the combustion chamber via the openings. In other words, the aforementioned fuel-air mixture is formed, for example, in the combustion chamber, or the fuel-air mixture is introduced into the combustion chamber. For example, fuel, in particular liquid fuel, and air are introduced into the combustion chamber. For example, the fuel is injected directly into the combustion chamber. The aforementioned mixture comprises the air and the fuel that are introduced into the combustion chamber.At least a portion of the mixture from the combustion chamber can flow through the openings and thus into the prechamber via the openings. In the prechamber, this portion of the mixture can be ignited and combusted, resulting in the previously described flares. The flares can then flow out of the prechamber via the openings and into the main combustion chamber, where they ignite and subsequently combust the remaining mixture remaining in the main combustion chamber. The respective opening has, for example, a respective flow cross-section through which the mixture or the respective flare can flow.

[0027] In order to be able to realize particularly advantageous operation, it is provided according to the invention that, with respect to an imaginary first plane running in the longitudinal direction of the prechamber and dividing the prechamber into two equal halves, a plurality of first openings are arranged in a first of the halves of the prechamber, with a plurality of second openings being arranged in the second half of the prechamber. The first openings are spaced apart in the circumferential direction of the prechamber by a respective first angle lying in the first half from an imaginary second plane running in the longitudinal direction of the prechamber and extending perpendicular to the first plane. The second openings are spaced apart in the circumferential direction of the prechamber by a respective second angle lying in the second half from the second plane. The mean value of all the first angles is smaller than the mean value of the or all the second angles.In order to achieve particularly advantageous operation, it is also provided that the planes intersect in an imaginary axis running in the longitudinal direction of the prechamber and thus of the prechamber spark plug as a whole. The openings are rotationally asymmetrical around the axis in which the planes are designed. In other words, the axis runs parallel to the longitudinal direction of the prechamber. The respective opening is designed as a bore. Alternatively or additionally, the flow cross-sections of at least two of the openings differ from one another in terms of their shape. The prechamber is designed to be rotationally symmetrical with respect to the axis. Advantages and advantageous embodiments of the first aspect of the invention are to be regarded as advantages and advantageous embodiments of the second aspect of the invention and vice versa.

[0028] Preferably, the internal combustion engine is designed as a reciprocating piston engine, whereby particularly advantageous operation can be ensured.

[0029] A third aspect of the invention relates to a motor vehicle, preferably designed as a motor vehicle, which has an internal combustion engine according to the second aspect of the invention. The motor vehicle can be driven by the internal combustion engine. Advantages and advantageous embodiments of the first and second aspects of the invention are to be regarded as advantages and advantageous embodiments of the third aspect of the invention, and vice versa.

[0030] Further advantages, features, and details of the invention will become apparent from the following description of a preferred embodiment and from the drawings. The features and combinations of features mentioned above in the description, as well as the features and combinations of features mentioned below in the description of the figures and / or shown alone in the figures, can be used not only in the respective specified combinations, but also in other combinations or on their own, without departing from the scope of the invention.

[0031] The drawing shows: Fig. 1 is a schematic and sectional side view of a prechamber spark plug according to the invention for a combustion chamber of an internal combustion engine of a motor vehicle; and Fig. 2 a schematic view of the pre-chamber spark plug along a Fig. 1 viewing direction marked B.

[0032] In the figures, identical or functionally identical elements are provided with the same reference symbols.

[0033] Fig. 1 shows a schematic and sectional side view of a pre-chamber spark plug 10 for a combustion chamber, for example formed by a cylinder or designed as a cylinder or at least partially delimited by a cylinder, of an internal combustion engine of a motor vehicle, in particular a motor vehicle such as a passenger car or a commercial vehicle, designed as a reciprocating piston engine. The motor vehicle is driven by the internal combustion engine. The pre-chamber spark plug 10 has at least or exactly one pre-chamber 12, the contour of which in Fig. 1 is designated 14. The pre-chamber 12 has several openings 16, also referred to as nozzles and designed as through-openings, which also look particularly good Fig. 2. The prechamber 12 is fluidically connectable or connected to the combustion chamber via the openings 16. In its fully manufactured state, the internal combustion engine has the aforementioned combustion chamber and the prechamber spark plug 10, so that in the fully manufactured state of the internal combustion engine, the prechamber 12 is fluidically connected to the combustion chamber via the openings 16. As a result, a fuel-air mixture, also referred to simply as a mixture, from the combustion chamber, also referred to as the main combustion chamber, can flow at least partially through the openings 16 and thereby into the prechamber 12, so that at least a portion of the fuel-air mixture, also referred to simply as a mixture, from the combustion chamber can flow through the openings 16 and thus flow or flows via the openings 16 into the prechamber 12. The combustion chamber is also delimited, for example, by a piston of the internal combustion engine.

[0034] The prechamber spark plug 10 has at least or exactly two electrodes 18 and 20 of an electrode device 22, which are arranged at least partially in the prechamber 12. In particular, respective free ends EN1 and EN2 of the electrodes 18 and 20 are arranged in the prechamber 12 and spaced apart from one another. The electrode 18 is designed, for example, as a so-called center electrode, with the electrode 20 being designed, for example, as a so-called ground electrode. By means of the electrode device 22, in particular by means of the electrodes 18 and 20, at least one ignition spark can be generated in the prechamber 12, in particular during fired operation of the internal combustion engine and / or within a respective working cycle of the internal combustion engine, in particular at an ignition location also referred to as the spark location.In particular, the ignition spark can be generated by means of the electrodes 18 and 20 between the electrodes 18 and 20, in particular between the ends EN1 and EN2, so that, for example, the electrodes 18 and 20, in particular the ends EN1 and EN2, form, define, delimit, or limit the ignition location. By means of the ignition spark, the mixture that has flowed into the prechamber 12 via the openings 16 can be ignited, whereby the mixture is combusted in the prechamber 12. This results in burning flares that flow through the openings 16 and thus flow out of the prechamber 12 into the combustion chamber via the openings 16. As a result, for example, a portion of the mixture remaining in the main combustion chamber is ignited and subsequently combusted, thereby driving the piston. In other words, the ignition spark can be generated or provided at the ignition location in the prechamber 12 by means of the electrodes 18 and 20.

[0035] In Fig. 1 and Fig. 2, a first imaginary plane E1 is visible, which runs in the longitudinal direction of the prechamber spark plug 10 and thus of the prechamber 12. In other words, the plane E1 runs parallel to the longitudinal direction of the prechamber 12 or the prechamber spark plug 10, wherein the longitudinal direction in Fig. 1 is illustrated by a double arrow 24. In addition, Fig. 1 and Fig. 2 an axis A can be seen, which is one or the main axis of the prechamber 12 and thus of the prechamber spark plug 10. The main axis is also referred to as the longitudinal axis or longitudinal central axis, wherein, for example, the prechamber 12 is rotationally symmetrical with respect to the axis A. For example, the openings 16 are arranged around the axis A, in particular along a circle, the center of which lies, for example, on the axis A. The axis A lies in or runs in the plane E1, wherein the plane E1 is perpendicular to the image plane of Fig. 1 and perpendicular to the image plane of Fig. 2 runs.

[0036] Out of Fig. 1 and Fig. 2 shows that the imaginary plane E1 divides or subdivides the prechamber 12 into two equal-sized halves H1 and H2, also referred to as chamber halves or prechamber halves. The first of the openings 16, designated B1, is arranged, in particular entirely, in the first half H1. The second of the openings 16, designated B2, is arranged, in particular entirely, in the second half H2.

[0037] In addition, Fig. 2, an imaginary or virtual second plane E2 can be seen. The second, imaginary plane E2 also runs parallel to the longitudinal direction or in the longitudinal direction of the prechamber 12 and thus of the prechamber spark plug 10, with the second plane E2 simultaneously running perpendicular to the first plane E1. The planes E1 and E2 intersect in the axis A, as can be seen particularly well from Fig. 2. Furthermore, Fig. 2 that the respective first opening B1 arranged in the first half H1 is spaced apart from the second plane E2 in the circumferential direction of the pre-chamber 12 and thus of the pre-chamber spark plug 10 by a respective first angle β1, which is located in particular in the first half H1 or on the side of the half H1 and extends, for example, in the circumferential direction of the pre-chamber 12. This is to be understood in particular that the respective opening B1 encloses a first angle β1 with the plane E2, which lies, for example, in the half H1. Accordingly, the respective second opening B2 arranged in the second half H2 is spaced apart from the second plane E2 in the circumferential direction of the pre-chamber 12 and thus of the pre-chamber spark plug 10 by a respective second angle β2, which is located, in particular, in the second half H2.This means that the respective second opening B2 arranged in the second half H2 encloses with the second plane E2 a respective second angle β2, for example lying in the second half H2 and extending, for example, in the circumferential direction of the prechamber 12.

[0038] Furthermore, the respective axes of the respective openings B1 and B2 are designated 26a and 26b, respectively. The axis 26a of one of the openings B1 runs in the plane E2. The respective axis 26a and 26b coincides with a respective passage direction along which the mixture can flow from the combustion chamber through the respective opening B1 and B2 and thus into the prechamber 12. In addition, the respective flare resulting from the ignition of the mixture in the prechamber 12 can flow through the respective opening B1 and B2 and thus flow from the prechamber 12 into the combustion chamber. The respective axis 26a and 26b encloses the respective first angle β1 and second angle β2 with the plane E2.

[0039] Furthermore, it is provided in the prechamber spark plug 10 that the mean value of the or all first angles β1 is smaller than the mean value of the or all second angles β2. As a result, the openings 16 cause an at least substantially tumble-shaped, i.e., cylindrical flow of the mixture flowing through the openings 16 and thereby flowing into the prechamber 12 via the openings 16, wherein the tumble-shaped flow of the mixture takes place or occurs in the prechamber 12. Furthermore, the or all openings 16 are straight or rectilinear over their entire extent. Due to the described design of the openings 16, the openings 16 are designed to generate the tumble-shaped flow of the mixture. This tumble-shaped flow of the mixture in the prechamber 12 is in Fig. 1 by arrows. The arrows show that the tumble-shaped flow is cylindrical in a cylindrical plane, where the cylindrical plane is, for example, parallel to the plane E2 or is the plane E2. In particular, the Fig. The arrows shown in Figure 1 represent a contour of the tumble-shaped flow, also known as the flow contour.

[0040] In particular, the tumble-shaped flow runs in a roller-like manner around one or the plane normal of the roller plane, whereby the plane normal runs, for example, in the plane E1 and perpendicular to the axis A.

[0041] Since the mean value of the first angle β1 is smaller than the mean value of the second angle β2, the openings 16 are designed or arranged rotationally asymmetrically around the axis A, whereby the tumble-shaped flow can be realized particularly advantageously. In particular, the tumble-shaped flow is thus brought about by the distribution of the openings 16 around the axis A and / or by a corresponding number of openings 16 and / or by a respective geometry of the openings 16, in particular their flow cross-sections. In particular, the respective angle β1 or β2 is a respective radial angle which is enclosed in the respective half H1 or H2 by the respective axis 26a or 26b and the plane E2. In particular, the angle β1 or β2 or the angular sector of β1 and β2 which has the smallest numerical value is used.In other words, the respective axis 26a or 26b can, in principle, enclose several angles with the plane E2, since the respective axis 26a or 26b is an infinite straight line and the plane E2 essentially extends infinitely. The respective angle β1 or β2 is the smallest of the angles enclosed by the respective axis 26a or 26b and the plane E2.

[0042] In addition, Fig. 1, EB denotes an electrode region in which, for example, the electrodes 18 and 20, in particular their ends EN1 and EN2, are arranged in the prechamber 12. Due to the tumble-shaped flow, a volume V of the prechamber 12, also referred to as the damage volume, can be kept particularly small, thus ensuring a particularly large operating range of the prechamber spark plug 10. Thus, particularly advantageous operation can be achieved.

[0043] The circumferential direction of the pre-chamber 12 runs around the axis A and is in Fig. 1 by a double arrow 28. As can be seen from Fig. As can be seen in Figure 2, the prechamber 12 can be divided into four quadrants by the planes E1 and E2. The planes E1 and E2 run perpendicular to each other, and the planes E1 and E2 intersect at the axis A, which thus runs in both planes E1 and E2.

[0044] The tumble flow has a flow center that is orthogonal to the main axis or axis A of the prechamber 12. The flow center is a roller axis around which the tumble flow runs in a roller-like manner. In this case, the roller axis runs perpendicular or orthogonal to plane E2 and, for example, in plane E1 or parallel to plane E1, so that plane E2 is the aforementioned roller plane. The tumble flow can be defined as a flow structure in which the flow of the mixture in the second half H2 flows upwards from the openings 16 towards the electrode region EB, which is also referred to as upward flow. The flow then flows through the electrode region EB, whereupon the flow flows downwards away from the electrode region EB and flows towards the openings 16, which is also referred to as downward flow.As a result, the tumble flow is a structured flow form, which, however, is not rotationally symmetrical to the prechamber main axis or to the main axis of the prechamber 12. List of reference symbols 10 pre-chamber spark plug 12 Antechamber 14 Contour 16 Opening 18 Electrode 20 electrodes 22 Electrode device 24 double arrow 26a, b axis 28 Double arrow A axis B1 opening B2 opening EB electrode area EN1 End EN2 End E1 level E2 level H1 half H2 half β1 angle β2 angle

Claims

[1] Prechamber spark plug (10) for a combustion chamber of an internal combustion engine, with a prechamber (12) having a plurality of openings (16, B1, B2), which is fluidically connectable to the combustion chamber via the openings (16, B1, B2) through which a fuel-air mixture can be introduced from the combustion chamber into the prechamber (12), wherein the respective opening (16, B1, B2) has a respective flow cross-section through which the fuel-air mixture can flow, wherein, with respect to an imaginary first plane (E1) running in the longitudinal direction (24) of the prechamber (12) and dividing the prechamber (12) into two equal halves (H1, H2), a plurality of first of the openings (16, B1, B2) are arranged in a first of the halves (H1, H2) and a plurality of second of the openings (16, B1, B2) are arranged in the second half (H2), wherein the first openings (B1) in the circumferential direction (28) of the pre-chamber (12) by a respective first angle (β1) from an imaginary,in the longitudinal direction (24) of the prechamber (12) and perpendicular to the first plane (E1) are spaced apart from the second plane (E2), wherein the second openings (B2) are spaced apart from the second plane (E2) in the circumferential direction (28) of the prechamber (12) by a respective second angle (β2), wherein the mean value of the first angles (β1) is smaller than the mean value of the second angles (β2), and wherein the openings (16) are designed to be rotationally asymmetrical about an imaginary axis (A) running in the longitudinal direction (24) of the prechamber (12) and in which the planes (E1, E2) intersect, and the prechamber (12) is designed to be rotationally symmetrical with respect to the axis (A), , characterized by , that: - the openings (16) are designed as bores; and / or - the flow cross-sections of at least two of the openings (16) differ from one another in terms of their shape. [2] Pre-chamber spark plug (10) according to claim 1, characterized by that the openings (16, B1, B2) are arranged along an imaginary circle whose center (M) lies on the axis (A), wherein the first plane (E1) divides the circle into two equal halves. [3] Pre-chamber spark plug (10) according to one of the preceding claims, characterized by that a number of the openings (B1) arranged in the first half (H1) is greater than a number of the openings (B2) arranged in the second half (H2). [4] Pre-chamber spark plug (10) according to one of the preceding claims, characterized by that the sum of the flow cross sections of the first openings (B1) arranged in the first half (H1) is greater than the sum of the flow cross sections of the second openings (B2) arranged in the second half (H2). [5] Pre-chamber spark plug (10) according to claim 4, characterized bythat the flow cross sections of the first openings (B1) arranged in the first half (H1) are larger than the flow cross sections of the second openings (B2) arranged in the second half (H2). [6] Pre-chamber spark plug (10) according to claim 4 or 5, characterized by that the mean value of the flow cross sections of the openings (B1) arranged in the first half (H1) is greater than the mean value of the flow cross sections of the openings (B2) arranged in the second half (H2). [7] Internal combustion engine for a motor vehicle, with at least one combustion chamber, and with a pre-chamber spark plug (10) assigned to the combustion chamber, which has a pre-chamber (12) having a plurality of openings (16, B1, B2) which is fluidically connected to the combustion chamber via the openings (16, B1, B2) via which a fuel-air mixture can be introduced from the combustion chamber into the pre-chamber (12), wherein the respective opening (16, B1, B2) has a respective flow cross-section through which the fuel-air mixture can flow, wherein, with respect to an imaginary first plane (E1) running in the longitudinal direction (24) of the pre-chamber (12) and dividing the pre-chamber (12) into two equal halves (H1, H2), a plurality of first of the openings (16, B1, B2) are arranged in a first of the halves (H1, H2) and a plurality of second of the openings (16, B1, B2) are arranged in the second half (H2),wherein the first openings (B1) are spaced apart in the circumferential direction (28) of the pre-chamber (12) by a respective first angle (β1) from an imaginary second plane (E2) running in the longitudinal direction (24) of the pre-chamber (12) and extending perpendicular to the first plane (E1), wherein the second openings (B2) are spaced apart in the circumferential direction (28) of the pre-chamber (12) by a respective second angle (β2) from the second plane (E2), wherein the mean value of the first angles (β1) is smaller than the mean value of the second angles (β2), and wherein the openings (16) are designed to be rotationally asymmetrical about an imaginary axis (A) running in the longitudinal direction (24) of the pre-chamber (12) and in which the planes (E1, E2) intersect, and the pre-chamber (12) is designed to be rotationally symmetrical with respect to the axis (A), characterized by , that: - the openings (16) are designed as bores; and / or - the flow cross-sections of at least two of the openings (16) differ from one another in terms of their shape. [8] Motor vehicle having an internal combustion engine according to claim 7.

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