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

Abstract

The invention relates to a pre-chamber ignition device (22) for a combustion chamber (18) of an internal combustion engine (10), comprising a pre-chamber (28), 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), 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, a first housing part (42) to which the spark plug (34) is attached, and a second housing part (44) which, in the installation position of the pre-chamber ignition device (22) towards the combustion chamber (18), adjoins the first housing part (42), is formed separately from the first housing part (42), is connected to the first housing part (42) and at least partially delimits the pre-chamber (28), and in which the connecting channels (30a, b) are trained,wherein the second housing part (44) is made of a metallic material which is a nickel-based alloy with a thermal conductivity of more than 50 W / mK.

Description

[0001] The invention relates to a prechamber 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 having at least one such prechamber spark plug.

[0002] It can be seen from EP 0 675 272 A1 that a prechamber ignition device for igniting an air-fuel mixture is known, with a prechamber which contains an electrode carrier protruding into the prechamber, to which at least one ignition electrode is fastened.

[0003] The object of the present invention is to provide a prechamber ignition device for an internal combustion engine and an internal combustion engine having at least one such prechamber ignition device, such that a particularly advantageous operation can be achieved.

[0004] This object is achieved 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 8. Advantageous embodiments with expedient further developments of the invention are specified in the respective claims.

[0005] 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, in particular as 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 piston engine, i.e. as a reciprocating piston machine and is also referred to as an internal combustion engine or internal combustion engine. The internal combustion engine has, for example, an output shaft, which can be designed, for example, as a crankshaft, in particular when the internal combustion engine is designed as a reciprocating piston engine or as a reciprocating piston machine.For example, the internal combustion engine has an engine housing, which is designed in particular as a cylinder housing, in particular as a cylinder crankcase, which is also referred to as an engine block and for example has, forms or delimits at least one cylinder. For example, a piston of the internal combustion engine is movably received in the cylinder, in particular in a translational manner, so that the piston and the cylinder each partially delimit the combustion chamber. The piston is articulated to the output shaft, in particular the crankshaft, via a connecting rod, for example, so that the translational movements of the piston in the cylinder can be converted into a rotational movement of the output shaft. The output shaft is thus rotatable 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.In particular during fired operation of the internal combustion engine, a fuel, in particular a liquid fuel, and air are introduced into the combustion chamber. The air, which is also referred to as fresh air, and the fuel form a fuel-air mixture, also simply referred to as a mixture, or are components of the mixture, which is at least temporarily taken up into the combustion chamber. The pre-chamber ignition device has a pre-chamber. Furthermore, the pre-chamber ignition device has a plurality of connecting channels via which the pre-chamber can be fluidically connected to the combustion chamber or is connected. In particular, it is provided that the pre-chamber is at least completely fluidically separated from the combustion chamber with the exception of the connecting channels, i.e. with the exception of a respective fluidic connection formed by the respective connecting channel between the pre-chamber and 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 otherwise fluidically separated from the combustion chamber, which is also referred to as the main combustion chamber. The mixture from the combustion chamber can be introduced into the pre-chamber via the connecting channels. If, for example, the piston moves from its bottom dead center to its top dead center, the mixture initially held in the combustion chamber, that is to say at least a portion of the mixture, is introduced, in particular pressed, from the combustion chamber via the connecting channels, that is to say through the connecting channels, into the pre-chamber.

[0006] The pre-chamber ignition device further comprises a spark plug, by means of which at least one ignition spark for igniting the fuel-air mixture in the pre-chamber can be generated in the pre-chamber, in particular within a respective working cycle of the internal combustion engine. In other words, the spark plug can provide or generate at least one ignition spark in the pre-chamber. By means of the ignition spark, in particular within the respective working cycle of the internal combustion engine, the mixture that has flowed into the pre-chamber and is thus at least temporarily held in the pre-chamber is ignited and thereby combusted. This results in so-called burning flares that flow through the connecting channels and thus penetrate into the combustion chamber via the connecting channels, where they ignite the mixture remaining in the combustion chamber, which is subsequently combusted. This drives the piston, for example.The spark plug is or comprises, for example, an electrode carrier that extends, in particular, into the prechamber, to which at least one ignition electrode is attached, which, for example, extends at least partially into the prechamber. The ignition spark can be generated in the prechamber by means of the ignition electrode.

[0007] The pre-chamber ignition device has a first housing part to which the spark plug is fastened. Very particularly, the spark plug is formed separately from the first housing part and fastened to the first housing part. Very particularly, it is provided that the first housing part is formed separately from the engine housing and is at least indirectly fastened to the engine housing. The aforementioned engine housing is also referred to as the first engine housing. The internal combustion engine has, for example, a second engine housing formed separately from the first engine housing, which is, for example, a cylinder head. The second engine housing is at least indirectly connected to the first engine housing. For example, the second engine housing forms a combustion chamber roof for the combustion chamber, by which the combustion chamber is partially delimited.In this case, it is preferably provided that the first housing part is formed separately from the second motor housing and is fastened to the second motor housing, in particular directly. For this purpose, for example, the first housing part is screwed into the second motor housing, in particular directly. The first housing part is formed separately from the second motor housing, separately from the first motor housing, and preferably the spark plug is formed separately from the second motor housing, separately from the first motor housing, and separately from the first housing part.

[0008] The pre-chamber ignition device also has a second housing part which is formed separately from the first housing part and is preferably formed separately from the first engine housing, separately from the second engine housing and separately from the spark plug. The second housing part is connected, in particular directly, to the first housing part, for example in that the second housing part is materially connected, in particular welded, to the first housing part. In the installed position of the pre-chamber ignition device, which assumes its installed position in the fully manufactured state of the internal combustion engine having the pre-chamber ignition device, the second housing part adjoins the first housing part towards the combustion chamber. The pre-chamber is at least partially and very preferably directly delimited by the second housing part.In other words, at least one part of the prechamber, also referred to as the first part, is delimited, in particular directly, by the second housing part, in particular by a jacket surface of the second housing part that contains the inner circumference, wherein the jacket surface of the second housing part that contains the inner circumference is also referred to as the first jacket surface that contains the inner circumference. It is conceivable that a second part of the prechamber is delimited, in particular directly, by the first housing part, in particular by a second jacket surface of the first housing part that contains the inner circumference. The aforementioned parts of the prechamber 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 via which the prechamber is or can be fluidically connected to the combustion chamber, main combustion chamber, are formed in the second housing part.Thus, it is preferably provided that the respective connecting channel is preferably completely circumferential along its respective circumferential direction and most preferably directly delimited by the second housing part. The respective connecting channel is thus a respective through-opening that completely penetrates the second housing part and, in the fully manufactured state of the internal combustion engine, opens at one end into the main combustion chamber and at the other end into the prechamber.

[0009] In order to be able to realize particularly advantageous operation, in particular full-load operation, of the internal combustion engine, it is provided according to the invention that the second housing part is formed, in particular exclusively, from a metallic material which is a nickel-based alloy (Ni-based alloy) with a thermal conductivity of more than 50 watts per millikelvin (W / mK). The medium-based alloy has a thermal conductivity of more than 50 watts per millikelvin at room temperature, i.e. at 20 degrees Celsius. In other words, the nickel-based alloy has the aforementioned thermal conductivity when, or in which, the nickel-based alloy has a temperature of 20 degrees Celsius.Due to this high thermal conductivity of the second housing part, heat can be particularly advantageously dissipated from the second housing part during fired operation of the internal combustion engine, in particular at least during full-load operation, and in particular can be transferred to or onto the first housing part, so that excessive temperatures in the second housing part can be effectively and efficiently avoided. This advantageously minimizes the pre-ignition tendency of the internal combustion engine, also referred to simply as a motor, particularly at high loads and engine speeds. This allows the internal combustion engine to achieve particularly high maximum power and particularly high maximum torque.

[0010] 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 greater mass compared to a standard hook spark plug. If no countermeasures are taken, the second housing part is subjected to particularly high thermal stress, particularly during full-load operation of the internal combustion engine. This can lead to excessively hot zones on and in the pre-chamber, whereby these hot zones are also referred to as hotspots. In unfavorable cases, these hotspots can lead to uncontrolled and undesired ignition of the mixture before the actual desired ignition point, which is also referred to as pre-ignition. In order to avoid such undesired pre-ignition, the invention provides that the second housing part is made of the temperature- and corrosion-resistant nickel-based alloy.This allows heat that has been introduced into the cap (second housing section) to flow away from the second housing section in a particularly advantageous manner. This prevents excessively high temperatures in the second housing section as well as in and around the prechamber, thus minimizing the engine's pre-ignition tendency, especially at high loads and speeds.

[0011] In principle, it would be conceivable for the first housing part to be formed from the same nickel-based alloy as the second housing part, so that heat introduced into the second housing part can flow particularly advantageously from the second housing part to the first housing part. Heat introduced into the first housing part can also advantageously flow away from the first housing part and be dissipated, for example, into the second engine housing, so that excessively high temperatures of the pre-chamber ignition device, particularly at and in the pre-chamber, can be advantageously avoided.

[0012] When reference is made above and below to the metallic material, unless otherwise stated, this refers to the metallic material from which the second housing part is formed. When reference is made above and below to the nickel-based alloy, this refers, unless otherwise stated, to the nickel-based alloy from which the second housing part is formed.

[0013] In order to be able to achieve a particularly high thermal conductivity of the nickel-based alloy and thus of the second housing part, it is provided in one embodiment of the invention that the nickel-based alloy is free of chromium as an alloying element, with the exception of any unavoidable impurities provided.

[0014] A further embodiment is characterized in that the nickel-based alloy has 1% to 5% by mass of iron (Fe), a maximum of 0.15% by mass of carbon (C), a maximum of 2% by mass of manganese (Mn), a maximum of 0.5% by mass of silicon (Si), a maximum of 0.5% by mass of aluminum (Al), a maximum of 28% to 34% by mass of copper (Cu), and the remainder nickel (Ni) with unavoidable or manufacturing-related impurities, whereby all components of the nickel-based alloy add up to 100% by mass. This makes it possible to achieve a particularly high thermal conductivity and a particularly high corrosion resistance of the second housing part, so that excessively high temperatures of the second housing part can be avoided. This makes it possible to keep the pre-ignition tendency of the internal combustion engine within a particularly low range.

[0015] 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.

[0016] To achieve particularly advantageous operation, a further embodiment of the invention provides that the first housing part is made of a second metallic material that is different from the nickel-based alloy. This allows for particularly high temperature and corrosion resistance of the prechamber ignition device.

[0017] A further embodiment is characterized in that the second metallic material is steel. This allows for particularly advantageous thermal conductivity of the first housing part as well, so that excessively high temperatures of the prechamber ignition device and thus the prechamber can be avoided.

[0018] In order to achieve, on the one hand, a particularly high level of robustness of the pre-chamber ignition device and, on the other hand, to be able to (still) dissipate heat advantageously from the pre-chamber ignition device, it is provided in a further embodiment of the invention that the second metallic material has a thermal conductivity which is lower than the thermal conductivity of the nickel-based alloy.

[0019] 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 reciprocating piston machine, for a simpler vehicle and preferably designed as a motor vehicle, in particular as 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.

[0020] In order to achieve particularly advantageous operation, one embodiment of the second aspect of the invention provides that the second housing part extends at least partially into the combustion chamber and is at least partially received or arranged in the combustion chamber. This ensures advantageous ignition of the mixture in the combustion chamber.

[0021] For all information, the components of the nickel-based alloy add up to 100% by mass.

[0022] 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 combinations specified, but also in other combinations or on their own, without departing from the scope of the invention.

[0023] The drawing shows: Fig. 1 shows a partial schematic sectional view of an internal combustion engine with a pre-chamber ignition device; Fig. 2 a partial schematic sectional view of the pre-chamber ignition device.

[0024] In the figures, identical or functionally identical elements are provided with the same reference symbols.

[0025] Fig. 1 shows a partial schematic sectional view of an internal combustion engine 10, also referred to as an internal combustion engine, combustion motor or engine, of a motor vehicle, also referred to simply as a vehicle, which is preferably designed as a motor vehicle, in particular as 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, which is preferably designed as a reciprocating piston engine or reciprocating piston machine, has an engine block designed, for example, as a cylinder housing, in particular as a cylinder crankcase, which in Fig. 1 can be seen in detail, is shown only very schematically and is designated by 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 delimits or forms the cylinder 14, in particular directly. A piston 16 of the internal combustion engine 10 is received in the cylinder 14 so as to be movable in translation. The internal combustion engine 10 has an output shaft, designed in particular as a crankshaft, via which the internal combustion engine 10 can provide torque for driving the motor vehicle. The piston 16 is connected in an articulated manner 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, the combustion chamber 18 of which 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 designed, for example, as a cylinder head. The second engine housing is preferably formed 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 assigned to the combustion chamber 18, which is also shown in FIG. Fig. 2 is shown in detail in a schematic sectional view.

[0026] The combustion chamber 18 is assigned at least one first gas exchange valve in the form of an inlet valve 24, via which air, also referred to as fresh air, can be introduced into the combustion chamber 18. In addition, a fuel, in particular a liquid fuel, can be introduced into the combustion chamber 18, in particular injected directly. The air and the fuel form a fuel-air mixture, also simply referred to as a mixture, which can be taken up or absorbed at least temporarily in 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. At least one second gas exchange valve in the form of an outlet valve 26 is assigned to the combustion chamber 18, via which the exhaust gas can be discharged from the combustion chamber 18.

[0027] Particularly good from a summary of Fig. 1 and Fig. 2 that the prechamber ignition device 22 has a prechamber 28 and a plurality of connecting channels 30 a, b. Via the connecting channels 30 a, b, the prechamber 28 is fluidically connected to the combustion chamber 18 and otherwise, in particular completely, fluidically separated from the combustion chamber 18. Via the connecting channels 30 a, b, as shown in Fig. 2 is illustrated by arrows 32, a first part of the mixture from the combustion chamber 18 (main combustion chamber) can be introduced into the prechamber 28, so that a remaining, second part of the mixture remains in the main combustion chamber (combustion chamber 18).

[0028] The prechamber ignition device 22 also has a spark plug 34. The spark plug 34 comprises an electrode carrier 36 and at least one ignition electrode 38, which is fastened, in particular directly, to the electrode carrier 36 and thus held. 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 prechamber 28. By means of the ignition spark, the first portion of the mixture flowing into the prechamber 28 can be ignited and subsequently combusted, which results in burning flares from the prechamber 28 flowing through the connecting channels 30a, b and thus flowing through the connecting channels 30a, b and thus flowing into the combustion chamber 18 via the connecting channels 30a, b.The burning flares ignite the second part of the mixture remaining in the combustion chamber 18, so that the second part of the mixture is also burned in the combustion chamber 18. This drives the piston 16 and thus, via the connecting rod, the output shaft, and thus rotates it relative to the first engine housing.

[0029] Associated with the ignition electrode 38 are, for example, ground electrodes and further electrodes 40. It can be seen that the ignition electrode 38 protrudes into the prechamber 28, and, for example, the respective further electrode 40 also protrudes into the prechamber 28. The spark plug 34 is formed separately from the engine housing.

[0030] 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 formed separately from one another. Furthermore, the respective housing part 42, 44 is formed 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 fastened to the second engine housing. For this purpose, the housing part 42 is, for example, screwed, in particular directly, into the second engine housing. As can be seen 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 one another and are connected to one another, in particular directly, in particular by the housing parts 42 and 44 being welded to one another, in particular directly. In the installed position of the prechamber ignition device 22, which has its in Fig. 1 and Fig. 2 in the fully manufactured state of the internal combustion engine 10 having the pre-chamber ignition device 22, the second housing part 44 adjoins the first housing part 42 towards the combustion chamber 18. Fig.1 shows that the housing part 44 is at least partially received in the combustion chamber 18 and thus protrudes into the combustion chamber 18. It can also be seen that the connecting channels 30a, b, in particular all of them, via which the prechamber 28 is fluidically connected to the combustion chamber 18, are formed in the second housing part 44.

[0031] It can be seen that the spark plug 34 is fastened, in particular directly, in 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.

[0032] In order to ensure particularly advantageous operation of the internal combustion engine 10 and the prechamber ignition device 22, the second housing part 44 is formed from a metallic material comprising a nickel-based alloy with a thermal conductivity of more than 50 watts per millikelvin (W / mK). In particular, the nickel-based alloy has a thermal conductivity of more than 50 watts per millikelvin at room temperature, i.e., at 20 degrees Celsius, i.e., when the nickel-based alloy has a temperature of 20 degrees Celsius. As a result, heat introduced into the housing part 44 can particularly advantageously flow away from or away from the housing part 44 and, for example, flow or stream to or onto the housing part 42.This makes it possible to avoid excessively high temperatures of the housing part 44 and in and around the prechamber 28, particularly at high loads or speeds of the internal combustion engine 10, especially during full-load operation of the internal combustion engine 10. This advantageously prevents an excessively high pre-ignition tendency of the internal combustion engine 10. List of reference symbols 10 Internal combustion engine 12 first engine housing 14 cylinders 16 cylinder pistons 18 combustion chamber 20 Combustion chamber roof 22 Pre-chamber ignition device 24 Inlet valve 26 Exhaust valve 28 Antechamber 30a, b connecting 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 first part T2 second part QUOTES CONTAINED IN THE DESCRIPTION

[0000] This list of documents submitted by the applicant was generated automatically and is included solely for the convenience of the reader. This list is not part of the German patent or utility model application. The DPMA assumes no liability for any errors or omissions. Cited patent literature

[0000] EP 0 675 272 A1

[0002]

Claims

[1] Pre-chamber ignition device (22) for a combustion chamber (18) of an internal combustion engine (10), with a pre-chamber (28), with a plurality of connecting channels (30a, b) via 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 for igniting the fuel-air mixture can be generated in the pre-chamber (28), with a first housing part (42) to which the spark plug (34) is fastened, and with a second housing part (44) which, in the installed position of the pre-chamber ignition device (22), adjoins the first housing part (42) towards the combustion chamber (18), is formed separately from the first housing part (42), is connected to the first housing part (42) and at least partially delimits the pre-chamber (28), in which second housing part the connecting channels (30a, b) are formed, characterized bythat the second housing part (44) is formed from a metallic material which is a nickel-based alloy with a thermal conductivity of more than 50 W / mK. [2] Pre-chamber ignition device (22) according to claim 1, characterized by that the nickel-based alloy is free from chromium as an alloying element, with the exception of any intended, unavoidable impurities. [3] Pre-chamber ignition device (22) according to claim 1 or 2 characterized by that the nickel-based alloy has: - 1% to 2.5% mass fraction of iron; - maximum 0.15% carbon by mass; - maximum 2% mass fraction of manganese; - maximum 0.5% mass fraction of silicon; - maximum 0.5% by mass of aluminium; - 28% to 34% mass fraction of copper; - and the rest is nickel with unavoidable impurities. [4] Pre-chamber ignition device (22) according to claim 3, characterized bythat the nickel-based alloy has at least 63% nickel by mass. [5] Pre-chamber ignition device (22) according to one of the preceding claims, characterized by that the first housing part (42) is formed from a second metallic material different from the nickel-based alloy. [6] Pre-chamber ignition device (22) according to claim 5, characterized by that the second metallic material is steel. [7] Pre-chamber ignition device (22) according to claim 5 or 6, characterized by that the second metallic material has a thermal conductivity which is lower than the thermal conductivity of the nickel-based alloy. [8] Internal combustion engine (10) for a motor vehicle, with at least one combustion chamber, to which a pre-chamber ignition device (22) according to one of the preceding claims is assigned. [9] Internal combustion engine (10) according to claim 8, characterized bythat the second housing part (42) projects at least partially into the combustion chamber (18).

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