Prechamber ignition device for an internal combustion engine and internal combustion engine for a motor vehicle

Abstract

Pre-chamber ignition device (22) for a combustion chamber (18) of an internal combustion engine (10), comprising a pre-chamber (28), with several connecting channels (30a, b) through which the pre-chamber (28) can be fluidically connected to the combustion chamber (18) and thereby a fuel-air mixture can be introduced from the combustion chamber (18) into the pre-chamber (28), with a spark plug (34) by means of which an ignition spark can be generated in the pre-chamber (28) to ignite the fuel-air mixture, with a first housing part (42) to which the spark plug (34) is attached, and with a second housing part (44) adjoining the first housing part (42) in the installation position of the pre-chamber ignition device (22) towards the combustion chamber (18), formed separately from the first housing part (42), connected to the first housing part (42) and at least partially delimiting the pre-chamber (28), in which the connecting channels (30a, b) are trained, characterized by,that the second housing part (44) is made of a metallic material which is a nickel-based alloy with a thermal conductivity of more than 26 W / mK and the first housing part (42) is made of a second metallic material different from the nickel-based alloy and the second metallic material has a thermal conductivity which is lower than the thermal conductivity of the nickel-based alloy.

Description

[0001] 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 claim 1. Furthermore, the invention relates to an internal combustion engine with at least one such pre-chamber spark plug.

[0002] EP 0 675 272 A1 discloses a pre-chamber ignition device for igniting a fuel-air mixture as is known, comprising a pre-chamber which contains an electrode carrier projecting into the pre-chamber, to which at least one ignition electrode is attached.

[0003] DE 10 2016 206 992 A1 discloses a pre-chamber ignition device for a combustion chamber of an internal combustion engine, comprising a pre-chamber and several connecting channels through which the pre-chamber can be fluidically connected to the combustion chamber, thereby allowing a fuel-air mixture to be introduced from the combustion chamber into the pre-chamber. A spark plug, attached to a first housing part, can generate an ignition spark in the pre-chamber to ignite the fuel-air mixture. Adjoining the first housing part, towards the combustion chamber, a second housing part, separate from the first housing part and the pre-chamber, is formed, in which the connecting channels are located. The second housing part is made of a metallic material, which is a nickel-based alloy with a thermal conductivity of more than 26 W / mK.The first housing part is made of a second metallic material that differs from the nickel-based alloy.

[0004] DE 23 41 821 A1 shows a mixture-compressing internal combustion engine with charge stratification and a second housing part made of a nickel-based alloy.

[0005] The material data sheet 2.4360 (NiCu30Fe / Alloy 400 / Monel®400) discloses a composition of a nickel-based alloy.

[0006] DE 10 2018 221 429 A1, DE 10 2019 125 479 A1 and DE 10 2020 103 863 A1 each disclose, considered individually, a pre-chamber ignition device for a combustion chamber of an internal combustion engine, comprising a pre-chamber and several connecting channels through which the pre-chamber can be fluidically connected to the combustion chamber, thereby allowing a fuel-air mixture to be introduced from the combustion chamber into the pre-chamber. Adjoining a first housing part, projecting towards and into the combustion chamber, a second housing part, at least partially confining the first housing part and the pre-chamber, is formed in which the connecting channels are located.

[0007] The object of the present invention is to provide a pre-chamber ignition device for an internal combustion engine and an internal combustion engine with at least one such pre-chamber ignition device, so that a particularly advantageous operation can be realized.

[0008] This problem is solved by a pre-chamber ignition device with the features of claim 1 and by an internal combustion engine with the features of claim 6. Advantageous embodiments with expedient further developments of the invention are specified in the respective claims.

[0009] A first aspect of the invention relates to a pre-chamber ignition device, also referred to as a pre-chamber spark plug, for a combustion chamber of an internal combustion engine, in particular of a motor vehicle. This means that the motor vehicle, also simply referred to as a vehicle and preferably designed as a motor vehicle, especially a passenger car, in its fully manufactured state, has the internal combustion engine and can be driven by means of the internal combustion engine, which is designed, for example, as a reciprocating engine, i.e., a piston engine, and is also referred to as an internal combustion engine or combustion engine. The internal combustion engine has, for example, an output shaft, which may be designed, for example, as a crankshaft, particularly when the internal combustion engine is designed as a reciprocating engine or a piston engine.For example, an internal combustion engine has an engine housing, in particular designed as a cylinder housing, especially as a cylinder crankcase, which is also referred to as an engine block and, for example, contains, forms, or defines at least one cylinder. A piston of the internal combustion engine is, for example, movably mounted in the cylinder, in particular translationally, so that the piston and the cylinder each partially define the combustion chamber. The piston is, for example, articulated to the output shaft, in particular the crankshaft, via a connecting rod, so that the translational movements of the piston in the cylinder can be converted into a rotational movement of the output shaft. Thus, the output shaft can rotate about an axis of rotation relative to the engine housing. The internal combustion engine can provide torque for driving the motor vehicle via the output shaft.Particularly during the firing of the internal combustion engine, fuel, especially liquid fuel, and air are introduced into the combustion chamber. The air, also referred to as fresh air, and the fuel form a fuel-air mixture, or are components of the mixture, which is at least temporarily drawn into the combustion chamber. The pre-chamber ignition system includes a pre-chamber. Furthermore, the pre-chamber ignition system has several connecting channels through which the pre-chamber can be fluidically connected to, or is connected to, the combustion chamber. Specifically, it is designed that the pre-chamber, with the exception of the connecting channels—that is, with the exception of the respective fluidic connection formed by each connecting channel between the pre-chamber and the combustion chamber—is at least completely fluidically separated from the combustion chamber.In other words, it is preferably provided that the pre-chamber is fluidically connected to the combustion chamber via the connecting channels and is otherwise fluidically separated from the combustion chamber, which is also referred to as the main combustion chamber. The mixture can be introduced from the combustion chamber into the pre-chamber via the connecting channels. For example, when the piston moves from its bottom dead center to its top dead center, the mixture initially taken up in the combustion chamber, that is, at least a portion of the mixture, is thereby introduced from the combustion chamber into the pre-chamber via the connecting channels, that is, through the connecting channels, and in particular, forced into it.

[0010] The pre-chamber ignition system further comprises a spark plug, by means of which at least one ignition spark can be generated in the pre-chamber, particularly during each operating cycle of the internal combustion engine, to ignite the fuel-air mixture in the pre-chamber. In other words, the spark plug can provide or generate at least one ignition spark in the pre-chamber. By means of this ignition spark, particularly during each operating cycle of the internal combustion engine, the mixture flowing into the pre-chamber and thus at least temporarily contained therein is ignited and thereby combusted. This results in so-called burning flares, which flow through the connecting channels and thus enter the combustion chamber via the connecting channels, igniting the mixture remaining in the combustion chamber, which is subsequently combusted. This, for example, drives the piston.The spark plug is, or comprises, for example, an electrode carrier that projects, in particular, into the pre-chamber, to which at least one ignition electrode is attached, which, for example, projects at least partially into the pre-chamber. The ignition electrode can generate the spark in the pre-chamber.

[0011] The pre-chamber ignition system has a first housing part to which the spark plug is attached. Specifically, the spark plug is designed separately from the first housing part and attached to it. In particular, the first housing part is designed separately from the engine housing and is attached to the engine housing, at least indirectly. The aforementioned engine housing is also referred to as the first engine housing. The internal combustion engine has, for example, a second engine housing, designed separately from the first engine housing, which may be a cylinder head. The second engine housing is connected to the first engine housing, at least indirectly. For example, the second engine housing forms a combustion chamber roof, which partially delimits the combustion chamber.It is preferably provided that the first housing part is designed separately from the second engine housing and is attached to the second engine housing, particularly directly. For this purpose, for example, the first housing part is screwed into the second engine housing, particularly directly. The first housing part is designed separately from the second engine housing, and preferably the spark plug is designed separately from the second engine housing, separately from the first engine housing, and separately from the first housing part.

[0012] The pre-chamber ignition device also comprises a second housing part, which is formed separately from the first housing part and is preferably separate from the first engine housing, the second engine housing, and the spark plug. The second housing part is connected to the first housing part, particularly directly, for example, by being bonded to it by a material connection, particularly by welding. In the installed position of the pre-chamber ignition device, which it assumes when the internal combustion engine containing the pre-chamber ignition device is fully assembled, the second housing part adjoins the first housing part towards the combustion chamber. The pre-chamber is at least partially, and preferably entirely, directly bounded by the second housing part.In other words, at least one part of the pre-chamber, also referred to as the first part, is bounded, in particular directly, by the second housing part, in particular by an inner circumferential surface of the second housing part, where the inner circumferential surface of the second housing part is also referred to as the first inner circumferential surface. It is conceivable that a second part of the pre-chamber is bounded, in particular directly, by the first housing part, in particular by a second inner circumferential surface of the first housing part. The aforementioned parts of the pre-chamber can be of the same size, or the first part can be larger than the second part, or the second part can be larger than the first part. Furthermore, it is provided that the, in particular all, connecting channels through which the pre-chamber is fluidically connected or connectable to the combustion chamber, main combustion chamber, are formed in the second housing part.It is therefore preferably provided that the respective connecting channel is preferably completely circumferential and most preferably directly bounded by the second housing part along its respective circumferential direction. The respective connecting channel is thus a respective through-opening that completely penetrates the second housing part and, in the fully assembled state of the internal combustion engine, opens at one end into the main combustion chamber and at the other end into the pre-chamber.

[0013] To achieve particularly advantageous operation, especially full-load operation, of the internal combustion engine, the invention provides that the second housing part is made, in particular exclusively, of a metallic material, which is a nickel-based alloy (Ni-based alloy) with a thermal conductivity of more than 26 watts per meter Kelvin (W / mK). The central base alloy exhibits a thermal conductivity of more than 26 watts per meter Kelvin at room temperature, i.e., at 20 degrees Celsius. In other words, the nickel-based alloy exhibits the aforementioned thermal conductivity when, or in which, the nickel-based alloy has a temperature of 20 degrees Celsius.Due to the high thermal conductivity of the second housing section, heat can be dissipated particularly advantageously from the second housing section during firing operation, especially at full load operation, and transferred to or onto the first housing section, thus effectively and efficiently preventing excessive temperatures in the second housing section. This advantageously minimizes the tendency of the internal combustion engine (also referred to simply as a motor) to pre-ignition, particularly at high loads and speeds. As a result, a particularly high maximum power output and a particularly high maximum torque can be achieved by the internal combustion engine.

[0014] The invention is based in particular on the following findings and considerations: The second housing part of the pre-chamber ignition device, also referred to as the cap, has a significantly larger mass compared to a standard hook spark plug. If no countermeasures are taken, this results in the second housing part being subjected to particularly high thermal stress, especially during full-load operation of the internal combustion engine. This can lead to excessively hot zones on and within the pre-chamber, which are also referred to as hotspots. In unfavorable cases, these hotspots can lead to uncontrolled and undesirable ignition of the mixture before the actual desired ignition point, which is also referred to as pre-ignition. To avoid such undesirable pre-ignition, the invention provides that the second housing part is made of a temperature- and corrosion-resistant nickel-based alloy.This allows heat that has entered the cap (second housing part) to dissipate particularly effectively from the second housing part. This prevents excessively high temperatures in the second housing part, as well as in and around the pre-chamber, thus minimizing the tendency for pre-ignition in the internal combustion engine, especially under high loads and speeds.

[0015] In principle, it would be conceivable for the first housing part to be made of the same nickel-based alloy as the second housing part, so that heat absorbed into the second housing part can dissipate particularly advantageously from the second housing part to the first housing part. This also allows heat absorbed into the first housing part to dissipate advantageously and be carried away, for example, into the second engine housing, thus advantageously preventing excessively high temperatures in and around the pre-chamber ignition system.

[0016] The first housing part is made of a second metallic material different from the nickel-based alloy. This allows for particularly high temperature and corrosion resistance of the pre-chamber ignition system.

[0017] In order to achieve a particularly high robustness of the pre-chamber ignition device on the one hand and to still be able to dissipate heat advantageously from the pre-chamber ignition device on the other hand, the invention provides that the second metallic material has a thermal conductivity which is lower than the thermal conductivity of the nickel-based alloy.

[0018] When the metallic material is mentioned before and below, this refers, unless otherwise specified, to the metallic material from which the second housing part is made. When the nickel-based alloy is mentioned before or below, this refers, unless otherwise specified, to the nickel-based alloy from which the second housing part is made.

[0019] In order to achieve a particularly high thermal conductivity of the nickel-based alloy and thus of the second housing part, one embodiment of the invention provides that the nickel-based alloy is free of chromium as an alloying element, with the exception of any unavoidable impurities that may be provided.

[0020] Another embodiment is characterized in that the nickel-based alloy contains 1% to 5% iron (Fe) by mass, at most 0.15% carbon (C) by mass, at most 2% manganese (Mn) by mass, at most 0.5% silicon (Si) by mass, at most 0.5% aluminum (Al) by mass, at most 28% to 34% copper (Cu) by mass, and nickel (Ni) as the remainder, with unavoidable or manufacturing-related impurities, wherein all components of the nickel-based alloy together constitute 100% by mass. This allows for particularly high thermal conductivity and corrosion resistance of the second housing part, thus preventing excessively high temperatures in the second housing part. This, in turn, keeps the pre-ignition tendency of the internal combustion engine to a particularly low level.

[0021] It has proven particularly advantageous if the nickel-based alloy has at least 63% nickel by mass, which ensures particularly high thermal conductivity and thus particularly high temperature resistance as well as particularly high corrosion resistance of the second housing part.

[0022] Another embodiment is characterized by the fact that the second metallic material is steel. This allows for a particularly advantageous thermal conductivity of the first housing part as well, so that excessively high temperatures of the pre-chamber ignition device and thus of the pre-chamber can be avoided.

[0023] A second aspect of the invention relates to an internal combustion engine, also referred to as an internal combustion engine, motor, or combustion engine, and preferably designed as a reciprocating piston engine, i.e., a piston engine, for a simpler vehicle, and preferably designed as a motor vehicle, in particular a passenger car, which has at least one combustion chamber to which a pre-chamber ignition device according to the first aspect of the invention is assigned. Advantages and advantageous embodiments of the first aspect are to be regarded as advantages and advantageous embodiments of the second aspect of the invention, and vice versa.

[0024] In order to achieve a particularly advantageous operation, one embodiment of the second aspect of the invention provides that the second housing part projects at least partially into the combustion chamber, with which it is at least partially received or arranged within the combustion chamber. This ensures advantageous ignition of the mixture in the combustion chamber.

[0025] All figures assume that the components of the nickel-based alloy together constitute 100% by mass.

[0026] Further advantages, features, and details of the invention will become apparent from the following description of a preferred embodiment and from the drawing. The features and combinations of features mentioned above in the description, as well as those mentioned below in the figure description and / or shown in the figures alone, can be used not only in the combinations specified, but also in other combinations or individually, without departing from the scope of the invention.

[0027] The drawing shows in: Fig. 1. Partial schematic sectional view of an internal combustion engine with a pre-chamber ignition device; Fig. 2. A schematic sectional view of the pre-chamber ignition device.

[0028] In the figures, identical or functionally equivalent elements are provided with the same reference symbols.

[0029] Fig. Figure 1 shows a partial schematic sectional view of an internal combustion engine 10, also referred to as an internal combustion engine, combustion engine, or motor, of a motor vehicle, which is preferably a motor car, and in particular a passenger car. This means that the motor vehicle, in its fully manufactured state, has the internal combustion engine 10 and can be driven by means of the internal combustion engine 10. The internal combustion engine 10, preferably designed as a reciprocating piston engine or reciprocating piston machine, has an engine block, for example, designed as a cylinder housing, and in particular as a cylinder crankcase, which is Fig. The engine block 12 is partially visible, depicted only very schematically, and labelled 12. The engine block 12 is also referred to as the first engine housing. The engine block 12 has at least one cylinder 14. This means, in particular, that the engine block 12 directly defines or forms the cylinder 14. A piston 16 of the internal combustion engine 10 is mounted in the cylinder 14 so as to be translationally movable. The internal combustion engine 10 has an output shaft, designed in particular as a crankshaft, via which the internal combustion engine 10 can provide torques for driving the motor vehicle. The piston 16 is articulated to the output shaft via a connecting rod, so that the translational movements of the piston 16 in the cylinder 14 can be converted into a rotational movement of the output shaft.The cylinder 14 and the piston 16 each partially delimit a combustion chamber 18 of the internal combustion engine 10, whose combustion chamber 18 is also partially delimited by a combustion chamber roof 20. The combustion chamber roof 20 is formed, for example, by a second engine housing of the internal combustion engine 10, the second engine housing of which is, for example, designed as a cylinder head. The second engine housing is preferably designed separately from the engine block 12 and connected to the engine block 12. The internal combustion engine 10 also has a pre-chamber ignition device 22 associated with the combustion chamber 18, which is also located in . Fig. 2 is shown in part in a schematic sectional view.

[0030] The combustion chamber 18 is assigned at least one first gas exchange valve in the form of an inlet valve 24, through which air, also referred to as fresh air, can be introduced into the combustion chamber 18. Furthermore, a fuel, particularly a liquid fuel, can be introduced into the combustion chamber 18, especially by direct injection. The air and the fuel form a fuel-air mixture, also simply referred to as a mixture, which can be drawn into or received at least temporarily into the combustion chamber 18. The mixture in the combustion chamber 18, also referred to as the main combustion chamber, can be ignited by means of the pre-chamber ignition device 22 and thereby combusted, resulting in exhaust gas from the internal combustion engine 10. The combustion chamber 18 is assigned at least one second gas exchange valve in the form of an exhaust valve 26, through which the exhaust gas can be discharged from the combustion chamber 18.

[0031] Especially good from a combination of Fig. 1 and Fig. 2 It is evident that the pre-chamber ignition device 22 has a pre-chamber 28 and several connecting channels 30 a, b. The pre-chamber 28 is fluidically connected to the combustion chamber 18 via the connecting channels 30 a, b and is otherwise, in particular completely, fluidically separated from the combustion chamber 18. As shown in Fig. As illustrated by arrows 32, a first part of the mixture can be introduced from the combustion chamber 18 (main combustion chamber) into the pre-chamber 28, so that a remaining, second part of the mixture remains in the main combustion chamber (combustion chamber 18).

[0032] The pre-chamber ignition device 22 also includes a spark plug 34. The spark plug 34 comprises an electrode carrier 36 and at least one ignition electrode 38, which is attached, in particular directly, to the electrode carrier 36 and thus held in place. By means of the ignition electrode 38, which in this case is designed as a center electrode, and thus by means of the spark plug 34, at least one ignition spark can be generated, i.e., provided, in the pre-chamber 28. By means of the ignition spark, the first part of the mixture flowing into the pre-chamber 28 can be ignited and subsequently combusted, resulting in burning flares from the pre-chamber 28 flowing through the connecting channels 30 a, b and thus flowing into the combustion chamber 18 via the connecting channels 30 a, b.The burning torches ignite the second part of the mixture remaining in combustion chamber 18, so that this second part of the mixture is also burned in combustion chamber 18. This drives the piston 16 and thus, via the connecting rod, the output shaft, rotating it relative to the first engine housing.

[0033] For example, ground electrodes and further electrodes 40 are associated with the ignition electrode 38. It can be seen that the ignition electrode 38 projects into the pre-chamber 28, and the respective additional electrode 40 also projects into the pre-chamber 28. The spark plug 34 is separate from the engine housing.

[0034] The pre-chamber ignition device 22 has at least or exactly two housing parts, namely a first housing part 42 and a second housing part 44. The housing parts 42 and 44 are designed separately from each other. Furthermore, the respective housing parts 42 and 44 are designed separately from the spark plug 34 and separately from the engine housing. For example, the housing part 42, and via it the pre-chamber ignition device 22, are attached to the second engine housing. For this purpose, the housing part 42 is, for example, screwed directly into the second engine housing. This is evident from Fig. 2 is that a first part T1 of the prechamber 28 is delimited, in particular directly, by the housing part 42, in particular by a first inner circumferential surface 46 of the housing part 42. A second part T2 of the prechamber 28 is delimited, in particular directly, by the second housing part 44, in particular by a second inner circumferential surface 48 of the housing part 44. The housing parts 42 and 44 are formed separately from each other and are connected, in particular directly, to each other, in particular by the fact that the housing parts 42 and 44 are welded together, in particular directly. In the installed position of the prechamber ignition device 22, which has its in Fig. 1 and Fig. In the installation position shown in 2, when the internal combustion engine 10, which has the pre-chamber ignition device 22, is fully assembled, the second housing part 44 connects to the first housing part 42 towards the combustion chamber 18. Fig.Figure 1 shows that the housing part 44 is at least partially enclosed in the combustion chamber 18 and thus projects into the combustion chamber 18. It is also apparent that the connecting channels 30 a, b, in particular all of them, through which the pre-chamber 28 is fluidically connected to the combustion chamber 18, are formed in the second housing part 44.

[0035] It can be seen that the spark plug 34 is attached, in particular directly, to the first housing part 42. For this purpose, for example, the spark plug 34, in particular the electrode carrier 36, is screwed, in particular directly, into the housing part 42.

[0036] To ensure particularly efficient operation of the internal combustion engine 10 and the pre-chamber ignition device 22, the second housing part 44 is made of a metallic material, specifically a nickel-based alloy with a thermal conductivity of more than 26 watts per meter Kelvin (W / mK). In particular, the nickel-based alloy exhibits a thermal conductivity of more than 26 watts per meter Kelvin at room temperature, i.e., at 20 degrees Celsius. This allows heat introduced into the housing part 44 to dissipate particularly efficiently and flow away from it, for example, to the housing part 42.This prevents excessively high temperatures of the housing part 44 and in and on the pre-chamber 28, particularly under high loads or speeds of the internal combustion engine 10, and especially during full-load operation of the internal combustion engine 10. This also advantageously prevents an excessively high tendency for pre-ignition of the internal combustion engine 10. Reference symbol list 10 Internal combustion engine 12 first engine casing 14 cylinders 16 cylinder pistons 18 Combustion chamber 20 Combustion chamber roof 22 Prechamber ignition device 24 Inlet valve 26 Exhaust valve 28 Antechamber 30a, b connection channel 32 arrows 34 Spark plug 36 electrode carriers 38 Ignition electrode 40 Additional electrode 42 first housing part 44 second housing part 46 first inner circumferential surface 48 second inner circumferential surface T1 Part One T2 Part Two

Claims

[1] Pre-chamber ignition device (22) for a combustion chamber (18) of an internal combustion engine (10), comprising a pre-chamber (28), with several connecting channels (30a, b) through which the pre-chamber (28) can be fluidically connected to the combustion chamber (18) and thereby a fuel-air mixture can be introduced from the combustion chamber (18) into the pre-chamber (28), with a spark plug (34) by means of which an ignition spark can be generated in the pre-chamber (28) to ignite the fuel-air mixture, with a first housing part (42) to which the spark plug (34) is attached, and with a second housing part (44) adjoining the first housing part (42) in the installation position of the pre-chamber ignition device (22) towards the combustion chamber (18), formed separately from the first housing part (42), connected to the first housing part (42) and at least partially delimiting the pre-chamber (28), in which the connecting channels (30a, b) are trained, characterized by, that the second housing part (44) is made of a metallic material which is a nickel-based alloy with a thermal conductivity of more than 26 W / mK and the first housing part (42) is made of a second metallic material which is different from the nickel-based alloy and the second metallic material has a thermal conductivity which is lower than the thermal conductivity of the nickel-based alloy. [2] Prechamber ignition device (22) according to claim 1, characterized by that the nickel-based alloy is free of chromium as an alloying element, with the exception of any unavoidable impurities that may be intended. [3] Prechamber ignition device (22) according to claim 1, or 2 characterized by , that the nickel-based alloy exhibits: - 1% to 2.5% iron by mass; - maximum 0.15% mass fraction of carbon; - maximum 2% mass fraction of manganese; - maximum 0.5% mass fraction silicon; - maximum 0.5% mass fraction of aluminum; - 28% to 34% copper by mass; - and the remainder being nickel with unavoidable impurities. [4] Prechamber ignition device (22) according to claim 3, characterized by that the nickel-based alloy contains at least 63% nickel by mass. [5] Prechamber ignition device (22) according to claim 1, characterized by that the second metallic material is steel. [6] Internal combustion engine (10) for a motor vehicle, comprising at least one combustion chamber to which a pre-chamber ignition device (22) is assigned according to one of the preceding claims. [7] Internal combustion engine (10) according to claim 6, characterized by , that the second housing part (44) protrudes at least partially into the combustion chamber (18).

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