Prechamber ignition means for an internal combustion engine, in particular of a motor vehicle, and internal combustion engine, in particular for a motor vehicle

Abstract

The invention relates to a prechamber ignition means (7) for an internal combustion engine (1), with a prechamber (8), with a plurality of overflow openings (9), via which the prechamber can be fluidically connected to a combustion chamber (2) of the internal combustion engine (1) and at least part of a mixture comprising fuel and air can be introduced from the combustion chamber (2) into the prechamber (8), and with a spark plug (10) which has an ignition electrode (11), by means of which at least one ignition spark can be produced in the prechamber (8) between the ignition electrode (11) and a corresponding ground electrode (12) in order to ignite the part which is introduced via the overflow openings (9) into the prechamber (8), wherein the spark plug (10), having the ignition electrode (11), and the ground electrode (12) are configured as structurally separate components.

Description

[0001] Pre-chamber ignition device for an internal combustion engine, in particular of a motor vehicle, and internal combustion engine, in particular for a motor vehicle

[0002] The invention relates to a pre-chamber ignition device for 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, in particular for a motor vehicle, with at least one such pre-chamber ignition device.

[0003] DE 102016 206 992 A1 discloses a prechamber spark plug comprising a housing, an ignition electrode, and a ground electrode. US Pat. No. 8,839,762 B1 discloses a system for igniting a mixture in an internal combustion engine. DE 102018 007 093 A1 discloses a prechamber spark plug for a combustion chamber of an internal combustion engine. Furthermore, DE 102020 106 397 A1 discloses a spark-ignited reciprocating piston internal combustion engine with a prechamber ignition system.

[0004] The object of the present invention is to provide a pre-chamber ignition device for an internal combustion engine, in particular of a motor vehicle, and an internal combustion engine, in particular for a motor vehicle, so that unfavorable combustions can be avoided.

[0005] This object is achieved according to the invention by a pre-chamber ignition device having the features of patent claim 1 and by an internal combustion engine having the features of patent claim 15. Advantageous embodiments of the invention are the subject of the dependent claims.

[0006] A first aspect of the invention relates to a pre-chamber ignition device, also referred to as a pre-chamber ignition system, for an internal combustion engine, in particular of a motor vehicle. This means that the internal combustion engine, in its fully manufactured state, has the pre-chamber ignition device. Furthermore, it is provided, for example, that the aforementioned motor vehicle, also simply referred to as a vehicle and designed, for example, as a motor vehicle, in particular as a passenger car, has the internal combustion engine and thus the pre-chamber ignition device and can be driven by the internal combustion engine. Very preferably, the internal combustion engine is designed as a reciprocating piston machine, thus as a reciprocating piston engine. The internal combustion engine is also referred to as an internal combustion engine or motor.The prechamber ignition device has a prechamber and a plurality of overflow openings, which are designed in particular as through-openings. The prechamber is fluidically connectable or can be fluidly connected to a combustion chamber of the internal combustion engine, also referred to as the main combustion chamber, via the overflow openings. At least a portion of a fuel-air mixture, which is initially received or can be received in the main combustion chamber and is also simply referred to as a mixture, can be introduced from the combustion chamber into the prechamber via the overflow openings. The mixture comprises, in particular, a liquid fuel and air. The mixture can optionally comprise at least one further component, such as recirculated exhaust gas.This means that the internal combustion engine, in its fully manufactured state, has the combustion chamber and the prechamber ignition device associated with the combustion chamber, the prechamber of which is fluidically connected to the combustion chamber via the transfer openings and, for example, is otherwise fluidically separated from the combustion chamber. In other words, it is preferably provided that the transfer openings form or are the only fluidic connections between the main combustion chamber and the prechamber. The transfer openings open, on the one hand, in particular at one end, into the prechamber. On the other hand, in particular at the other end, the transfer openings open into an area surrounding the prechamber device.In the fully manufactured state of the internal combustion engine, the surrounding area is the main combustion chamber, so that in the fully manufactured state of the internal combustion engine, the transfer openings on the other hand, in particular at the other end, open into the combustion chamber (main combustion chamber). As a result, in the fully manufactured state of the internal combustion engine, the prechamber is fluidically connected to the combustion chamber via the transfer openings and is preferably otherwise fluidically separated from the combustion chamber. The prechamber and thus the prechamber ignition device are used in particular to carry out prechamber ignition, in particular during fired operation of the internal combustion engine and very particularly within a respective working cycle of the internal combustion engine.In particular, it is provided that the pre-chamber is completely fluidically separated from the combustion chamber, with the exception of respective fluidic connections formed by the respective overflow openings between the pre-chamber and the combustion chamber. In the fully manufactured state of the internal combustion engine, the combustion chamber is delimited, for example, partly by a piston and, for example, partly by a cylinder in which the piston can be accommodated so as to be movable, in particular in a translational manner. For example, in particular within the respective working cycle of the internal combustion engine, the said mixture is formed in the combustion chamber and / or the mixture is introduced into the combustion chamber, so that, in particular within the respective working cycle of the internal combustion engine, the mixture is initially accommodated in the combustion chamber.At least the aforementioned portion of the mixture flows from the combustion chamber (main combustion chamber) through the transfer ports and thus into the prechamber via the transfer ports, particularly when the piston moves toward or into its top dead center position. This means that, particularly during the respective combustion cycle, at least the portion of the mixture from the main combustion chamber is introduced into the prechamber via the transfer ports. The portion of the mixture flowing through the transfer ports and thus flowing from the combustion chamber into the prechamber via the transfer ports is also referred to as the first portion of the mixture.In particular, it is conceivable that the piston, particularly on its path toward or at its top dead center, conveys at least the first portion of the mixture from the main combustion chamber through the transfer openings and thereby into the prechamber, whereby at least the first portion of the mixture is introduced into the prechamber. In this case, it is particularly conceivable that a second portion of the mixture remains in the main combustion chamber and thus, in particular, outside the prechamber.

[0007] The pre-chamber ignition device also has a spark plug, also referred to as an ignition element, by means of which at least one ignition spark can be generated in the pre-chamber and in particular within the respective working cycle to ignite the first part introduced into the pre-chamber via the overflow openings. When reference is made above or below to the part, this means the first part unless otherwise stated. Thus, for example, in particular within the respective working cycle, the mixture flowing into or introduced into the pre-chamber, i.e. the first part, is ignited, in particular by the ignition spark being generated in the pre-chamber by means of the spark plug, in particular within the respective working cycle. The spark plug has, in particular precisely, an ignition electrode, which is also referred to as the center electrode or can be designed as a center electrode.By means of the ignition electrode, at least one or exactly one ignition spark for igniting the portion of the mixture introduced into the prechamber via the overflow openings can be generated between the ignition electrode and a corresponding ground electrode. It is preferably provided that the prechamber ignition device has the ground electrode as the only ground electrode for generating the ignition spark. Thus, it is preferably provided that the prechamber ignition device has at least two electrodes, namely the ignition electrode and the ground electrode, between which, in particular within the respective working cycle, at least one or exactly one ignition spark can be generated. By means of the ignition spark, the mixture flowing into the prechamber and thus received in the prechamber, i.e. the first portion, is ignited and thereby burned.As a result, the mixture ignited and subsequently burning in the prechamber flows from the prechamber through the transfer ports and back into the main combustion chamber, for example in the form of burning flares or jets flowing through the transfer ports. Because the burning mixture from the prechamber flows through the transfer ports and thus flows from the prechamber into the main combustion chamber via the transfer ports, the remaining mixture in the combustion chamber, i.e., the aforementioned second portion, is ignited and subsequently burned. This drives the piston, for example, and moves it toward its bottom dead center or into its bottom dead center.

[0008] In order to avoid unfavorable, undesired ignitions and combustions of the mixture and thus ensure particularly advantageous, especially fired, operation of the internal combustion engine, the invention provides that the spark plug, which has the ignition electrode, and the ground electrode are designed as structurally separate components. It is preferably provided that the spark plug itself, i.e., considered on its own, has the ignition electrode, but is free of a ground electrode corresponding to the ignition electrode.The feature that the spark plug and the ground electrode are designed as structurally separate components is to be understood in particular as follows: When reference is made to the components above and below, this means, unless otherwise stated, the spark plug and the ground electrode, so that, for example, the spark plug is a first of the components and the ground electrode is a second of the components. In the fully manufactured state of the internal combustion engine having the pre-chamber ignition device, the first component and the second component, thus the spark plug and the ground electrode, are mounted, for example, on a third component of the internal combustion engine, in particular in such a way that the first component and the second component are fastened to the third component.For example, the first component and the second component are mounted or fastened to the third component in such a way that both relative movements between the first component and the third component and relative movements between the second component and the third component as well as relative movements between the first component and the second component are prevented. For example, the third component is a cylinder head of the internal combustion engine. For example, the cylinder head forms a combustion chamber roof associated with the combustion chamber, which partially delimits the combustion chamber. The piston is movable within the cylinder and relative to the combustion chamber, for example, translationally.Since the spark plug and the ground electrode are now designed as structurally separate components, the spark plug can be disassembled from the third component, i.e. detached and moved away from the third component, independently of the second component, i.e. while the second component remains mounted on the third component, in particular in such a way that relative movements between the third component and the second component are prevented. Furthermore, it is possible, for example, that, in particular in a method for producing the internal combustion engine, the second component is first mounted, in particular fastened, to the third component independently of the first component, in particular in such a way that relative movements between the second component and the third component are prevented, while the first component is not (yet) mounted on the third component, and is therefore still detached and spaced from the third component.For example, the first component can be mounted, in particular fastened, to the third component only after the second component has been completely mounted to the third component, in particular in such a way that relative movements between the first component and the third component are prevented.In other words, the ground electrode is not a component of the spark plug, so that mounting of the ground electrode on the third component does not involve or have to involve mounting of the spark plug on the third component and / or mounting of the spark plug on the third component does not involve or have to involve mounting of the ground electrode on the third component and / or dismounting of the spark plug from the third component does not involve or has to involve dismounting of the ground electrode from the third component, thus so that the spark plug can be dismounted from the third component without this involving dismounting of the ground electrode from the third component, i.e. while the ground electrode remains mounted on the third component.This structural separation of the spark plug and the ground electrode prevents excessive heating of the ground electrode, particularly during the fired operation of the internal combustion engine, thus preventing unfavorable, unwanted ignitions and / or combustion of the mixture. The invention is based in particular on the following findings and considerations: Since, particularly during the respective combustion cycle, the mixture from the combustion chamber flows through the transfer openings and thereby flows into the prechamber via the transfer openings, in particular being transported or conveyed into the prechamber via the transfer openings by means of the piston, the prechamber is a so-called passive prechamber.In order to achieve a particularly high, particularly specific, power output of an internal combustion engine, e.g., a gasoline engine, a particularly large prechamber volume is desirable, so that, for example, the prechamber volume is at least 0.2% of the displacement of the internal combustion engine. Since the prechamber of the prechamber ignition device according to the invention is a passive prechamber, the prechamber is a prechamber that is, in particular, only flushed on the combustion chamber side with the mixture, also referred to as fuel gas. Such a passive prechamber can lead to advantageously rapid combustion in the main combustion chamber, particularly in gasoline engines.This occurs due to the ignition of the mixture within the pre-chamber, also known as pre-ignition, and due to the flares, also known as torch jets, which flow through the transfer openings at high speed and thus flow from the pre-chamber into the combustion chamber via the transfer openings and create multiple combustion sites in the combustion chamber. Compared to conventional solutions, combustion in the main combustion chamber can take place more than twice as fast. This drastically reduces the need for pre-ignition. This means that high power densities can be achieved even without using a substoichiometric combustion air ratio (enrichment). In order to advantageously keep the combustion duration short and, in particular, to reduce it to such an extent that enrichment can be avoided, engines designed particularly as gasoline engines can be used.

[0009] Internal combustion engines with high power densities require large-volume prechambers, such as the prechamber of the prechamber ignition device according to the invention. However, single-piece spark plugs, also known as prechamber spark plugs, or conventional spark plugs in conjunction with separate prechambers, are prone to pre-ignition or glow ignition, particularly at high prechamber volumes, due to excessive temperatures of components of the prechamber spark plug or the conventional spark plug. It has been found that the ground electrode of conventional spark plugs or prechamber spark plugs, in particular, is prone to overheating in conjunction with a high prechamber volume. Furthermore, the prechamber volume of single-piece prechamber spark plugs is limited both thermally and by the combustion chamber in the cylinder head.In conventional spark plugs and conventional pre-chamber spark plugs, the ground electrode is an integral part of the spark plug or pre-chamber spark plug, so that the conventional pre-chamber spark plug or spark plug is an inseparable unit with the ignition electrode, which is designed, for example, as a center electrode, and the ground electrode.

[0010] The structural separation of the spark plug and the ground electrode provided by the invention prevents excessive heating of the ground electrode. This prevents unwanted pre-ignition and glow ignition, thus ensuring effective and efficient operation of the internal combustion engine. In particular, the structural separation of the spark plug from the ground electrode, or vice versa, makes it possible to construct the ground electrode with a particularly solid construction and thus equip it with a particularly high mass, allowing the ground electrode to exhibit a higher heat capacity compared to conventional solutions. This reduces the maximum temperature of the ground electrode during a combustion cycle compared to conventional solutions.On the other hand, a particularly advantageous, large-area connection of the ground electrode to the third component, in particular to the cylinder head, can be achieved, enabling improved heat conduction compared to conventional solutions. This means that, compared to conventional solutions, heat can be transferred or dissipated more effectively from the ground electrode to the third component, thus avoiding excessively high temperatures at the ground electrode.

[0011] In order to avoid undesired ignitions and combustions and thus to be able to ensure particularly advantageous operation of the internal combustion engine, it is provided in one embodiment of the invention that the pre-chamber ignition device has a housing element which is designed separately from the spark plug and separately from the ground electrode and preferably also separately from the third component, in which the spark plug is at least partially, in particular at least predominantly and thus at least more than half, received, that is to say arranged.

[0012] It has proven particularly advantageous if the ground electrode is supported directly on the housing element and thus, in particular, rests directly against the housing, allowing heat to be dissipated from the ground electrode in a particularly advantageous manner. Apart from the direct support of the ground electrode on the housing element, there is no direct connection between the ground electrode and the housing element, so that the ground electrode is not directly connected to the housing element. This allows, for example, a particularly advantageous, in particular structural, separation of the spark plug from the ground electrode, or vice versa, to be achieved, so that excessively high temperatures of the ground electrode can be advantageously avoided.

[0013] In order to advantageously design the spark plug and the ground electrode as structurally separate components, on the one hand, and to realize simple and thus time- and cost-effective production of the internal combustion engine, on the other hand, it is provided in a further embodiment of the invention that the ground electrode is directly connected to the housing element. In the fully manufactured state of the internal combustion engine, for example, the housing element is mounted, in particular directly, on the third component, in particular such that relative movements between the housing element and the third component are prevented. For example, the housing element is directly connected to the third component, in particular such that the housing element is screwed directly to the third component.Since, for example, it is intended that the ground electrode be directly connected to the housing element, mounting the housing element on the third component is accompanied by mounting the ground electrode on the third component, or vice versa, so that the internal combustion engine can be manufactured quickly and cost-effectively. Furthermore, this allows heat to be transferred from the ground electrode to the housing element, for example, from the housing element to the third component, thereby avoiding excessively high temperatures of the ground electrode.

[0014] It has proven particularly advantageous if the ground electrode is welded directly to the housing element, particularly by friction welding. This allows heat to be transferred from the ground electrode to the housing element and thus dissipated by the ground electrode, thus preventing excessively high temperatures at the ground electrode and thus unwanted, unfavorable combustion and ignition of the mixture.

[0015] In a further, particularly advantageous embodiment of the invention, the spark plug is screwed directly to the housing element and thus directly connected to the housing element. Preferably, the spark plug is screwed to the housing element in a non-destructively detachable manner and thus connected. This allows for simple, advantageous production of the internal combustion engine, while simultaneously ensuring an advantageous structural separation between the spark plug and the ground electrode.

[0016] For example, the spark plug, in particular a housing of the spark plug, has a first thread, in particular in the form of a first external thread. For example, the housing element has a second thread corresponding to the first thread, in particular in the form of a first internal thread. It is preferably provided that the first thread and the second thread are screwed directly together, in particular such that the first external thread is screwed directly into the first internal thread.

[0017] A further embodiment is characterized in that the prechamber ignition device has the cylinder head for the internal combustion engine, which is formed separately from the spark plug, separately from the ground electrode, and separately from the housing element. The housing element, the spark plug, and the ground electrode are each arranged at least partially within the cylinder head. For example, the ground electrode and / or the housing element are arranged entirely within the cylinder head. This allows heat to be transferred particularly advantageously from the ground electrode directly to the cylinder head and / or via the housing element to the cylinder head, so that excessively high temperatures and thus unfavorable combustion and ignition of the mixture can be avoided.

[0018] It has proven particularly advantageous if the housing element is screwed directly to the cylinder head, thus connecting it directly to the cylinder head. In particular, the housing element is screwed to the cylinder head in a non-destructive manner. This allows the internal combustion engine to be manufactured particularly quickly and cost-effectively. On the other hand, this allows heat to be transferred from the housing element to the cylinder head and thus dissipated away from the ground electrode, thus advantageously preventing excessively high temperatures at the ground electrode.

[0019] For example, the housing element has a third thread, in particular in the form of a second external thread, wherein, for example, the cylinder head has a fourth thread corresponding to the third thread, in particular in the form of a second internal thread. For example, the third thread and the fourth thread are screwed directly to one another, as a result of which the housing element is screwed directly to the cylinder head. In this case, for example, the second external thread is screwed directly into the second internal thread. It is preferably provided that, in particular with the exception of at least one or exactly one direct contact between the ground electrode and the cylinder head and / or with the exception of at least one or exactly one electrically conductive connection between the ground electrode and the cylinder head, a direct connection between the ground electrode and the cylinder head is avoided.This ensures a particularly advantageous structural separation between the spark plug and the ground electrode, so that excessively high temperatures of the ground electrode can be avoided.

[0020] It has proven particularly advantageous if the ground electrode is screwed directly to the cylinder head. This allows heat to be transferred particularly advantageously from the ground electrode directly to the cylinder head, whereby excessively high temperatures of the ground electrode can be reliably avoided. For example, the third thread, which is particularly designed as an external thread, extends, in particular continuously, over the housing element and the ground electrode, in particular over a first outer circumferential surface of the housing element and a second outer circumferential surface of the ground electrode, so that preferably both the housing element and the ground electrode are screwed directly to the fourth thread and thus directly to the cylinder head by means of the third thread.This allows for a particularly advantageous mechanical and, in particular, thermal connection of both the housing element and the ground electrode to the cylinder head, allowing heat to be transferred particularly advantageously from the ground electrode to the cylinder head and directly to the housing element, and via the housing element to the cylinder head. This advantageously prevents excessively high temperatures of the ground electrode.

[0021] In order to be able to realize particularly advantageous combustion, a further embodiment of the invention provides that a first part of the prechamber is delimited, in particular directly, by a first housing part that is formed separately from the spark plug, separately from the ground electrode and separately from the housing element and preferably also separately from the third component. For example, a first partial region of the first housing part is arranged in the third component, for example, a second partial region of the first housing part projects into the main combustion chamber. For example, the, in particular all, overflow openings are formed, in particular each completely, in the first housing part, so that, for example, the respective overflow opening is designed as a respective through-opening that penetrates the first housing part, in particular completely, and which is also referred to as a through-flow opening.A second part of the prechamber is delimited, in particular directly, by a second housing part formed separately from the spark plug, separately from the ground electrode, separately from the housing element, separately from the first housing part, and preferably also separately from the third component. Preferably, the second part is larger than the first part. This advantageously ensures a particularly large volume of the prechamber, and unfavorable combustion and ignition can be advantageously avoided.

[0022] It has proven particularly advantageous to design the housing components separately from the cylinder head. This creates particularly favorable thermal conditions, preventing excessively hot spots and thus unfavorable, unwanted combustion and ignition.

[0023] For example, the second housing part is arranged, in particular completely, in the cylinder head, wherein, for example, the second housing part can be arranged, in particular completely, outside the combustion chamber.

[0024] In a further, particularly advantageous embodiment of the invention, the first housing part is formed from a first material, while the second housing part is formed from a second material that differs from the first material. Preferably, the first material is a metallic material. Alternatively or additionally, the second material can be a metallic material. This allows particularly advantageous thermal conditions to be created, so that excessively hot spots and thus unwanted ignitions and burns can be avoided.

[0025] The first material is preferably a nickel-based alloy, with the first material most preferably being Inconel®. The second material is preferably copper or a copper alloy. In particular, the second material is, for example, a copper-zirconium alloy. This allows for particularly advantageous thermal conditions to be created.

[0026] Finally, it has proven particularly advantageous if at least a third part of the prechamber, designed as a residual gas chamber, is delimited by the housing element, in particular directly. The third part is preferably smaller than the second part and smaller than the first part. In order to thereby realize particularly advantageous thermal conditions and, in particular, to avoid excessively high temperatures of the ground electrode, a further embodiment of the invention provides that at least a fourth part of the prechamber is arranged in a through-opening of the ground electrode and is thus delimited, in particular directly, by the ground electrode, the through-opening of the ground electrode opening at one end directly into the second part and the other end directly into the third part. The fourth part is preferably smaller than the third part and smaller than the second part and preferably smaller than the first part.

[0027] In order to particularly advantageously avoid excessively high temperatures of the ground electrode, a further embodiment of the invention provides for the ground electrode to be disk-shaped, i.e., designed as a disc. In this case, the ground electrode is cylindrical on its outer circumference, for example.

[0028] A further embodiment is characterized in that the ground electrode has an engagement opening designed as a through-opening, which is provided in particular in addition to the through-opening in which the fourth part is arranged, wherein the ignition electrode, designed, for example, as a center electrode, engages in the engagement opening. This allows, for example, the ground electrode to be provided with a particularly high mass in order to advantageously avoid excessively high temperatures of the ground electrode.

[0029] Finally, it has proven particularly advantageous if the ground electrode is sealed against the second housing part by means of at least one sealing device. For example, the sealing device is or comprises at least or precisely one sealing element, in particular formed separately from the ground electrode and separately from the second housing part, and preferably also separately from the first housing part and separately from the housing element, by means of which the ground electrode is sealed against the second housing part. For example, the sealing device, in particular the sealing element, rests on the one hand against the ground electrode and on the other hand against the second housing part, in particular directly in each case.The sealing device, in particular the sealing element, can be designed as a solid body, whereby, for example, the sealing device, in particular the sealing element, can be formed from a metallic material such as copper. Furthermore, it would be conceivable for the sealing device, in particular the sealing element, to be designed as a liquid seal. The sealing element can be used to advantageously seal the prechamber, thus enabling particularly advantageous, efficient operation.

[0030] A second aspect of the invention relates to an internal combustion engine, also referred to as an internal combustion engine or motor and preferably designed as a reciprocating piston engine, i.e., a reciprocating piston machine, which has at least one pre-chamber ignition device according to the first aspect of the invention. 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. The internal combustion engine preferably has at least one or more combustion chambers, wherein a pre-chamber ignition device according to the first aspect of the invention is assigned to the respective combustion chamber, in particular precisely.

[0031] Further details of the invention will become apparent from the following description of a preferred embodiment with the accompanying drawings. In the drawings:

[0032] Fig. 1 shows a schematic sectional view of a

[0033] Internal combustion engine for a motor vehicle, with a pre-chamber ignition device;

[0034] Fig. 2 shows a partial schematic and sectional exploded view of the pre-chamber ignition device; and

[0035] Fig. 3 shows a further schematic sectional view of the

[0036] Internal combustion engine.

[0037] In the figures, identical or functionally identical elements are provided with the same reference numerals.

[0038] Fig. 1 shows a partial schematic sectional view of an internal combustion engine 1, also referred to as a motor or internal combustion engine and designed as a reciprocating piston engine, thus as a reciprocating piston machine, for a motor vehicle, also simply referred to as a vehicle. This means that the motor vehicle, in its fully manufactured state, has the internal combustion engine 1 and can be driven by the internal combustion engine 1. The internal combustion engine 1 has at least one combustion chamber 2, which is partially delimited by a cylinder 3, partially by a piston 4, and partially by a combustion chamber roof 5. The cylinder 3 is formed by a cylinder housing of the internal combustion engine 1, designed, for example, as a cylinder crankcase.The piston 4 is arranged in the cylinder 3 for translational movement and is thus translationally movable relative to the cylinder housing between a top dead center and a bottom dead center. The combustion chamber roof 5 is formed by a cylinder head 6 of the internal combustion engine 1, wherein the cylinder head 6 is formed separately from the cylinder housing and connected to the cylinder housing.

[0039] The internal combustion engine 1 has a pre-chamber ignition device 7, which can, for example, encompass the cylinder head 6. Fig. 2 shows a schematic, sectional, and perspective exploded view of a section of the pre-chamber ignition device 7, which is also simply referred to as a pre-chamber system or pre-chamber device. The pre-chamber ignition device 7 has a pre-chamber 8, which is particularly clearly visible in Fig. 3, as well as several overflow openings 9 designed as through-openings, via which the pre-chamber 8 is fluidically connected to the combustion chamber 2, also referred to as the main combustion chamber, of the internal combustion engine 1. The pre-chamber 8 is fluidically connected to the combustion chamber 2 via the overflow openings 9 and is otherwise completely fluidically separated from the combustion chamber 2.A fuel-air mixture, also simply referred to as a mixture, comprising a preferably liquid fuel and air, can be introduced from the combustion chamber 2 into the prechamber 8 via the overflow openings 9.

[0040] It can be seen particularly well from a combination of Fig. 1 and 3 that the pre-chamber ignition device 7 has a spark plug 10 which has an ignition electrode 11 designed, for example, as a center electrode. By means of the ignition electrode 11, at least one ignition spark can be generated in the pre-chamber 8 between the ignition electrode 11 and a corresponding ground electrode 12, in particular within a respective working cycle of the internal combustion engine 1. In particular, within the respective working cycle of the internal combustion engine 1, a first part of the mixture flows from the main combustion chamber via the overflow openings 9 into the pre-chamber 8, and for example, a second part of the mixture remains in the main combustion chamber (combustion chamber 2). By means of the ignition spark, the part of the mixture that flowed into the pre-chamber 8 can be ignited and thus burned within the respective working cycle.The ignited and thus combusted mixture flows through the transfer openings 9 and thus out of the pre-chamber 8 via the transfer openings 9 and into the main combustion chamber (combustion chamber 2), where the burning first portion of the mixture ignites and thereby combusts the second portion of the mixture. This drives, for example, the piston 4.

[0041] In order to prevent excessively high temperatures of the ground electrode 12 and thus undesirable, unfavorable ignition and combustion of the mixture, the spark plug 10, which has the ignition electrode 11, and the ground electrode 12 are designed as structurally separate components. The spark plug 10 itself, i.e., considered on its own, is free of its own ground electrode corresponding to the ignition electrode 11.

[0042] The pre-chamber ignition device 7 has a housing element 13 which is formed separately from the spark plug 10, separately from the ground electrode 12 and separately from the cylinder head 6 and which, as will be explained in more detail below, is designed or functions as an adapter socket. In the exemplary embodiment shown in the figures, the ground electrode 12 is designed as a disk which is cylindrical and thus circular on the outer circumference. As will be explained in more detail below, the ground electrode 12 has a plurality of and thus at least or exactly two through-openings 14 which completely penetrate the ground electrode 12. Furthermore, the ground electrode 12 has an engagement opening 15 which is provided in addition to the through-openings 14 and is designed as a further through-opening which completely penetrates the ground electrode 12. The ignition electrode 11 engages in the particularly central engagement opening 15 of the ground electrode 12.In the exemplary embodiment shown in the figures, the housing element 13 is at least partially arranged in the cylinder head 6, and the ground electrode 12 is arranged entirely in the cylinder head 6. The spark plug 10 is arranged at least partially in the cylinder head 6 and at least partially in the housing element 13. In the exemplary embodiment shown in the figures, the ground electrode 12 is connected directly to the housing element 13, for example in such a way that the ground electrode 12 is directly welded to the housing element 13 by friction welding and is thereby connected. Alternatively, it would be conceivable for the ground electrode 12 to be supported directly on the housing element 13, wherein apart from this direct support of the ground electrode 12 on the housing element 13, a direct connection between the ground electrode 12 and the housing element 13 is not provided, i.e. is omitted. In the exemplary embodiment shown in the figuresIn the exemplary embodiment shown, the spark plug 10 is screwed directly to the housing element 13. For this purpose, the spark plug 10 has a first thread 21 in the form of a first external thread, and the housing element 13 has a second thread 22 in the form of a first internal thread corresponding to the first thread 21. The first external thread is screwed directly into the first internal thread. In the exemplary embodiment shown in the figures, the housing element 13 and the ground electrode 12 form a third thread 16 in the form of a second external thread, so that the third thread 16 extends, so to speak, in particular continuously over at least part of the housing element 13 and at least part of the ground electrode 12, and is therefore formed at least in a partial region of the housing element 13 and at least a partial region of the ground electrode 12.In other words, the housing element 13 has a first threaded part of the thread 16, and the ground electrode 12 has a second threaded part of the thread 16, wherein in particular the threaded parts merge directly and preferably flush with one another. The cylinder head 6, which is formed separately from the housing element 13 and separately from the ground electrode 12, has a fourth thread 17 in the form of a second internal thread corresponding to the third thread 16, wherein the third thread 16 and the fourth thread 17 are directly screwed to one another, in particular such that the second external thread is screwed directly into the second internal thread. As a result, both the housing element 13 and the ground electrode 12 are each directly screwed to the cylinder head 6, in particular each screwed directly into the cylinder head 6. Furthermore, it is clear from Fig.It can be seen that, for example, the spark plug 10 can be detached from the housing element 13 and from the cylinder head 6 and thus disassembled, in particular unscrewed, while the housing element 13 and the ground electrode 12 are screwed to the cylinder head 6 and thus remain mounted and attached to the cylinder head 6. This structural separation between the spark plug 10 on the one hand and the ground electrode 12 on the other hand can prevent an excessively high temperature of the ground electrode 12.

[0043] In the exemplary embodiment shown in the figures, a first part T1 of the pre-chamber 8 is delimited, in particular directly, by a first housing part 18. A second part T2 of the pre-chamber 8, which is larger in particular than the first part T1, is delimited, in particular directly, by a second housing part 19, wherein the housing parts 18 and 19 are preferably formed separately from one another and are connected, in particular directly, to one another. For example, the housing parts 18 and 19 are welded directly to one another, in particular by friction welding, and are thus directly connected to one another. Very preferably, the housing part 18 is formed from a first material, in particular a metallic material, and the housing part 19 is formed, for example, from a second material, in particular a metallic material, which is different from the first material.For example, the first material is a nickel-based alloy, for example Inconel®, wherein the second material is, for example, a copper alloy, in particular a copper-zirconium alloy. The housing element 13 is formed, for example, from a third material, which is, for example, a different material from the first material. For example, the third material corresponds to the second material, or the third material is a different material from the second material. The cylinder head 6 is formed, for example, from a fourth material. Preferably, the fourth material is a metallic material. Preferably, the third material is a metallic material. Preferably, the fourth material is a different material from the third material and / or from the second material and / or from the first material.In particular, the fourth material is aluminum or an aluminum alloy. Preferably, the third material has a first coefficient of thermal expansion, with the fourth material, for example, having a second coefficient of thermal expansion. Preferably, the difference between the first coefficient of thermal expansion and the second coefficient of thermal expansion is at most 6, in particular at most 5, and most particularly at most 4. For example, the coefficient of thermal expansion of the fourth material is 17, with the coefficient of thermal expansion of the third material, for example, being 17. This makes it possible to avoid excessive, thermally induced relative movements and thus stresses between the housing element 13 and the cylinder head 6.

[0044] Since the housing parts 18 and 19 are connected to one another, in particular directly, the housing parts 18 and 19 form a lower housing part, also simply referred to as a lower part. Preferably, when the lower housing part and the cylinder head 6 are viewed in isolation, i.e. solely by considering the lower housing part and the cylinder head 6, the lower housing part is connected, in particular directly, to the cylinder head 6, in particular in such a way that the housing part is pressed onto the cylinder head 6, in particular pressed into the cylinder head 6. From Fig. 3 it can be seen that the housing part 19 is arranged completely in the cylinder head 6. A first part of the housing part 18 is arranged in the cylinder head 6, and a second part of the housing part 18 is arranged outside the cylinder head 6 and projects into the main combustion chamber. In this case, the overflow openings 9, in particular all of them, are arranged in the second part of the housing part 18.In particular, it can be seen that the, in particular all, overflow openings 9 are formed in the housing part 18.

[0045] The pre-chamber ignition device 7 further comprises a sealing device referred to as a sealing element 20, wherein the sealing element 20 is formed separately from the housing parts 18 and 19, separately from the ground electrode 12, separately from the cylinder head 6, separately from the housing element 13, and also separately from the spark plug 10. The sealing element 20 is arranged here between the ground electrode 12 and the lower housing part, in particular the housing part 19, in particular such that the sealing element 20 is supported, on the one hand, in particular directly, on the ground electrode 12 and, on the other hand, in particular directly, on the housing part 19 and thus bears against it. In the present case, the sealing element 20 is designed as a sealing ring. By means of the sealing element 20, the ground electrode 20 is sealed against the second housing part 19.

[0046] The fact that the housing lower part is pressed onto the cylinder head 6 provides a particularly advantageous heat transfer between the housing lower part and the cylinder head 6, thus avoiding excessively high temperatures. In particular, it is conceivable that the housing part 19 and / or the housing part 18 are pressed onto the cylinder head 6, in particular directly. For example, the sealing element 20 is formed from a metallic material such as copper.For example, with the exception of the fact that the sealing element 20, which is designed as a sealing ring, for example, is supported, in particular directly, on the ground electrode 12 and, in particular directly, on the housing part 19, a direct connection between the sealing element 20 and the ground electrode 12 and between the sealing element 20 and the housing part 19 is not provided, that is to say not formed, so that with the exception of the fact that the sealing element 20 bears, in particular directly, on the ground electrode 12 and on the housing part 19, the sealing element 20 is not connected to the ground electrode 12 and not to the housing part 19.

[0047] It can be seen particularly well from Fig. 1 and 3 that at least or exactly two third parts T3 of the prechamber 8, designed as residual gas chambers, are delimited, in particular directly, by the housing element 13. For example, the respective volumes of the residual gas chambers together make up at least 30 percent of the total volume of the prechamber 8. For each third part T3, a respective fourth part T4 of the prechamber 8 is arranged in the respective through-opening 14 of the ground electrode 12, so that a number of residual gas chambers corresponds to a number of fourth parts T4 or through-openings 14. Thus, the respective fourth parts T4 are formed, in particular directly, by the ground electrode 12. The through-openings 14 of the ground electrode 12 open directly into the third part T3 on the one hand and directly into the second part T2 on the other.In this way, a particularly large volume of the pre-chamber 8 can be realized in a space-saving manner, the volume of which is, for example, exactly or at least 1,000 cubic millimeters.

[0048] Since the third material and the fourth material have the same or similar thermal expansion coefficients, heat can be transferred particularly well from the housing element 13 to the cylinder head 6. Furthermore, heat can be transferred particularly well from the ground electrode 12 to the housing element 13 and directly to the cylinder head 6, so that advantageous heat dissipation away from the ground electrode 12 can be achieved. This can prevent excessive temperatures of the ground electrode 12. Furthermore, it can be seen that the spark plug 10 is mounted or held on the cylinder head 6 via the housing element 13, so that the housing element 13 is designed or functions as an adapter sleeve or adapter bushing.

[0049] Each residual gas chamber is or contains a respective residual gas volume in which residual gas can be stored. The residual gas volume can be designed to be particularly large.

[0050] By means of the ignition electrode 11, the ignition spark can be generated between the ignition electrode 11 and the ground electrode 12 at an ignition location, also referred to as the ignition point. The respective residual gas chamber, and thus the respective residual gas volume, is arranged on a side of the ignition location facing away from the main combustion chamber and thus above the ignition location. Such an arrangement of the respective residual gas volume above the ignition location contributes to particularly advantageous mixture formation at the ignition location, since the residual gas, which is always present, is concentrated here.

[0051] For example, from Fig. 2, it can be seen that the number of residual gas chambers and thus the number of through-openings 14 is four, so that, for example, the ground electrode 12 has a total of exactly five through-openings, namely the through-openings 14 and the engagement opening 15. However, this is only exemplary in the present case, but is nevertheless advantageous.

[0052] Internal combustion engine combustion chamber cylinder piston

[0053] combustion chamber roof cylinder head

[0054] Pre-chamber ignition device Pre-chamber overflow opening Spark plug

[0055] Ignition electrode Ground electrode Housing element Through hole Access hole Third thread Fourth thread First housing part Second housing part

[0056] Sealing element first thread second thread first part second part third part fourth part

Claims

Patent claims 1. Pre-chamber ignition device (7) for an internal combustion engine (1), with a pre-chamber (8), with a plurality of overflow openings (9), via which the pre-chamber (8) can be fluidically connected to a combustion chamber (2) of the internal combustion engine (1) and at least a portion of a mixture comprising fuel and air can be introduced from the combustion chamber (2) into the pre-chamber (8), and with a spark plug (10) which has an ignition electrode (11), by means of which at least one ignition spark for igniting the portion introduced into the pre-chamber (8) via the overflow openings (9) via the ignition electrode (11) can be generated in the pre-chamber (8), characterized in that the spark plug (10) having the ignition electrode (11) and the ground electrode (12) are designed as structurally separate components.

2. Pre-chamber ignition device (7) according to claim 1, characterized by a housing element (13) formed separately from the spark plug (10) and separately from the ground electrode (12), in which the spark plug (10) is at least partially accommodated.

3. Pre-chamber ignition device (7) according to claim 2, characterized in that the ground electrode (12) is supported directly on the housing element (13), wherein apart from the direct support of the ground electrode (12) on the housing element (13), a direct connection between the ground electrode (12) and the housing element (13) is omitted.

4. Pre-chamber ignition device (7) according to claim 2, characterized in that the ground electrode (12) is directly connected to the housing element (13).

5. Pre-chamber ignition device (7) according to claim 4, characterized in that the ground electrode (12) is welded directly to the housing element (13) and thereby connected.

6. Pre-chamber ignition device (7) according to one of claims 2 to 5, characterized in that the spark plug (11) is screwed directly to the housing element (13).

7. Pre-chamber ignition device (7) according to one of claims 2 to 6, characterized by a cylinder head (6) for the internal combustion engine (1) which is formed separately from the spark plug (11), separately from the ground electrode (12) and separately from the housing element (13), wherein the housing element (13), the spark plug (11) and the ground electrode (12) are each arranged at least partially in the cylinder head (6).

8. Pre-chamber ignition device (7) according to claim 7, characterized in that the housing element (13) is screwed directly to the cylinder head (6).

9. Pre-chamber ignition device (7) according to claim 7 or 8, characterized in that the ground electrode (12) is screwed directly to the cylinder head (6).

10. Pre-chamber ignition device (7) according to one of claims 2 to 9, characterized in that: - a first part (T1) of the prechamber (8) is delimited by a first housing part (18) formed separately from the spark plug (11), separately from the ground electrode (12) and separately from the housing element (13); and - a second part (T2) of the prechamber (8) is delimited by a second housing part (19) formed separately from the spark plug (11), separately from the ground electrode (12), separately from the housing element (13) and separately from the first housing part (18).

11. Pre-chamber ignition device (7) according to claim 10 in its reference to one of claims 7 to 9, characterized in that the housing parts (18, 19) are formed separately from the cylinder head (6).

12. Pre-chamber ignition device (7) according to claim 10 or 11, characterized in that the first housing part (18) is formed from a first material and the second housing part (19) is formed from a second material different from the first material.

13. Pre-chamber ignition device (7) according to one of claims 10 to 12, characterized in that: - at least a third part (T3) of the prechamber (8) designed as a residual gas chamber is delimited by the housing element (13); and - at least a fourth part (T4) of the prechamber (8) is arranged in a through-opening (14) of the ground electrode (12) and is thereby delimited by the ground electrode (12), the through-opening (14) of which opens at one end directly into the second part (T2) and at the other end directly into the third part (T3).

14. Pre-chamber ignition device (7) according to one of claims 10 to 13, characterized in that the ground electrode (20) is sealed against the second housing part (19) by means of at least one sealing device (20).

15. Internal combustion engine (1) with at least one pre-chamber ignition device (7) according to one of the preceding claims.

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