PRECHAMBER FOR AN INTERNAL COMBUSTION ENGINE, INTERNAL COMBUSTION ENGINE COMPRISING A PRECHAMBER OF THIS TYPE AND METHOD FOR DESIGNING AND/OR PRODUCING A PRECHAMBER OF THIS TYPE

Abstract

A prechamber for an internal combustion engine, including a surface that is situated in the interior of the prechamber and that is impinged by a flow during the operation of the prechamber. The surface has at least one first surface region and at least one second surface region, wherein the first surface region has a defined texture, whereas the second surface region is untextured.

Claims

1-9. (canceled)

10. A prechamber for an internal combustion engine, comprising: a surface that is subjected to flow during operation of the prechamber and which is arranged at an inner side of the prechamber, wherein the surface has at least a first surface region and at least a second surface region, wherein the first surface region has a specific structure, wherein the second surface region is free from the specific structure.

11. The prechamber according to claim 10, wherein the surface which is subjected to flow is a surface of an inner wall of the prechamber.

12. The prechamber according to claim 11, wherein the specific structure is constructed integrally or in multiple pieces with the inner wall.

13. The prechamber according to claim 10, wherein the specific structure has structural elements, which are a) spheroidal when viewed in longitudinal section and/or, b) tooth-like with a sharp or rounded tip when viewed in longitudinal section, and/or, c) circular when viewed from above, and/or, d) elliptical or oval when viewed from above, and/or, e) rectangular when viewed from above, and/or, f) drop-like when viewed from above, and/or g) triangular when viewed from above.

14. The prechamber according to claim 13, wherein the structural elements that are hemispherical in longitudinal section.

15. The prechamber according to claim 13, wherein the structural elements are square when viewed from above.

16. The prechamber according to claim 10, wherein the specific structure has structural elements that have a) a diameter or a width of from at least 0.02 mm to a maximum of 2 mm, and/or b) a height or a depth of from at least 0.02 mm to a maximum of 2 mm, and/or c) a length of from at least 0.04 mm to a maximum of 4 mm, and/or d) a spacing from each other of from at least 0.02 mm to a maximum of 1 mm, and/or e) a corner radius of from at least 0.01 mm to a maximum of 1 mm.

17. The prechamber according to claim 16, wherein the structural elements are spaced from each other from at least 0.04 mm to a maximum of 1 mm.

18. An internal combustion engine, comprising a prechamber according to claim 10.

19. The internal combustion engine according to claim 18, wherein the internal combustion engine is a gas engine.

20. A method for configuring and/or producing a prechamber for an internal combustion engine, comprising the steps of: providing a prechamber geometry of a prechamber having a surface that is subjected to flow during operation of the prechamber; simulating a gas flow at an inner side of the prechamber; identifying a surface region which is suitable for an application of the gas flow to the surface with regard to a stabilization of the gas flow; and providing a specific structure in the surface region, wherein the specific structure is provided so that the gas flow is applied to the surface in the region of the specific structure.

21. The method according to claim 20, wherein the surface of the prechamber has a second surface region without the specific structure.

Description

[0051] The invention is explained in greater detail below with reference to the drawings, in which:

[0052] FIG. 1 is a schematic illustration in two views of an embodiment of a prechamber, and

[0053] FIG. 2 shows a plurality of views of different embodiments of specific structures for the prechamber.

[0054] FIG. 1 shows an embodiment of a prechamber 1 of an internal combustion engine 2, wherein the prechamber 1 is illustrated in FIG. 1a) in a first plane of longitudinal section and in FIG. 1b) in a second plane of longitudinal section which is rotated about a longitudinal axis L with respect to the first plane of longitudinal section as a half-section. The prechamber 1 for the internal combustion engine 2 has a surface 3 which is subjected to flow during operation of the prechamber 1 and which is arranged at an inner side 5 of the prechamber 1. The surface 3 which is subjected to flow has a first surface region 7 and a second surface region 9, wherein the first surface region 7 has a specific structure 11 and wherein the second surface region 9 is free from this structure 11, wherein it thus does not have the specific structure 11. Preferably, the surface 3 is constructed in the second surface region 9 so as to be unstructured and/or smooth.

[0055] The second surface region 9 preferably extendswhen viewed in a peripheral directionfrom a first-in FIG. 1a) right-side of the first surface region 7 to a second-in FIG. 1a) left-side of the first surface region 7, that is to say, almost completely peripherally with the exception of a peripheral portion in which the first surface region 7 is arranged. However, it is also possible for the surface 3 to have more than a first surface region 7. Alternatively or additionally, it is possible for the surface 3 to have more than a second surface region 9.

[0056] A longitudinal direction extends in the direction of the longitudinal axis L illustrated in FIG. 1b). A peripheral direction engages around the longitudinal direction concentrically. A radial direction is perpendicular to the longitudinal direction.

[0057] The surface 3 is in this instance constructed as a surface of an inner wall 13, wherein the inner wall 13 surrounds the inner side 5 of the prechamber 1.

[0058] In FIG. 1b), it is illustrated that the specific structure 11 is constructed in this instance integrally with the inner wall 13, wherein it is preferably directly incorporated into the surface 3 or formed out of it.

[0059] At the inner side 5 of the prechamber 1, in a manner known per se an ignition device 15 or an ignition element 17 of the ignition device 15, for example, an electrode pair for producing a spark ignition, is arranged.

[0060] The inner side 5 is connected by means of at least one bore, in this instance specifically by means of a upward channel 19, and side channels 21 to a main combustion chamber which is not illustrated in the state of the prechamber 1 mounted on the internal combustion engine 2.

[0061] During a compression cycle of the internal combustion engine 2, a gas flow flows, in particular a combustion air/fuel admixture, via the side channels 21 and the upward channel 19 into the inner side 5 of the prechamber 1. In this instance, as a result of the specific structure 11, there is produced at the inner side 5 a defined flow field which is insensitive with respect to external fluctuations, in particular cyclical fluctuations, during operation of the internal combustion engine 2. In this instance, the specific structure 11 is arranged in the first surface region 7 in which a main flow of the gas flow is applied directly to the surface 3. In this instance, local turbulences are formed and the local turbulence kinetic energy is increased. This leads to a local pressure drop along the structured surface region 7. As a result of this local pressure drop, there is produced on the gas flow a force which leads to the application thereof to the structured surface region 7. The specific structure 11 is in this instance selected in such a manner that this force is greater than forces which are produced by cyclically changing influencing factors so that, compared with these influencing factors, a cyclically insensitive flow pattern is produced inside the prechamber 1.

[0062] FIG. 2 shows illustrations of a plurality of embodiments of specific structures 11. Elements which are identical and functionally identical are provided with the same reference numerals so that in this regard reference may be made to the above description. It has been found that the specific structure 11 preferably has a plurality of structural elements 23 which may in particular be constructed as protrusions and/or as recesses.

[0063] FIGS. 2a), 2b) and 2c) are each longitudinal sections through specific structures 11. In this instance, the structural elements 23 in the embodiment according to FIG. 2a) are constructed in particular in a hemispherical manner, consequently in a semi-spherical manner.

[0064] In FIG. 2b), the structural elements 23when viewed in longitudinal sectionare constructed in a triangular or tooth-like manner, wherein they have a sharp tip 25.

[0065] In FIG. 2c), the structural elements 23 are alsowhen viewed in longitudinal sectionconstructed in a triangular or tooth-like manner, wherein they, however, have a rounded tip 25 with a corner radius or radius of curvature. The corner radius or radius of curvature is preferably from at least 0.01 mm to a maximum of 1 mm.

[0066] A height H of the structural elements 23 which is illustrated in this instance by way of example in FIG. 2b) is generallyregardless of the specific shape of the structural elements 23preferably from at least 0.02 mm to a maximum of 2 mm. This preferably also applies accordingly to a depth of structural elements which are not constructed as protrusions but instead as recesses.

[0067] A spacing of adjacent structural elements 23 from each other which is designated A by way of example in FIG. 2c) isagain regardless of the specific shape of the structural elements 23preferably from at least 0.02 mm to a maximum of 1 mm, preferably from at least 0.04 mm to a maximum of 1 mm. In this instance, in a particularly preferred manner, in principle the shortest spacingregardless of the direction in which it extendsis considered between directly adjacent structural elements 23.

[0068] FIGS. 2d) to 2h) are plan views of specific structures 11, consequently as the same view on which the illustration of FIG. 1a) is also based.

[0069] In this instance, the structural elements 23 in the embodiment according to FIG. 2d) are constructed in a circular manner.

[0070] In the embodiment according to FIG. 2e), the structural elements 23when viewed from aboveare constructed in an elliptical or oval manner.

[0071] The structural elements 23 which are illustrated in FIGS. 2d) and e) may in particular be constructed in longitudinal section as illustrated in FIG. 2a).

[0072] FIG. 2f) illustrates an embodiment of the specific structure 11 in which the structural elements 23when viewed from aboveare constructed in a rectangular, in particular square manner. They may in particularwhen viewed in longitudinal sectionbe constructed as illustrated in FIG. 2b) or 2c).

[0073] FIG. 2g) illustrates an embodiment of the specific structure 11 in which the structural elements 23 have a drop-like form. In this instance, they are preferably in particular at an upper end facing the ignition device 15 constructed to be narrower than at a lower end facing away from the ignition device 15 and at an end facing a main combustion chamber which is not illustrated.

[0074] FIG. 2h) shows an embodiment of the specific structure 11 in which the structural elements 23 are constructed in a triangular manner.

[0075] The drop-like structural elements 23 according to FIG. 2g) canwhen viewed in longitudinal sectionbe constructed as illustrated in FIG. 2a), but it is also possible for them to be constructed as illustrated in FIG. 2b) or 2c). The triangular structural elements 23 according to FIG. 2h) arewhen viewed in longitudinal sectionpreferably constructed as illustrated in one of the Figures in FIG. 2b) or 2c).

[0076] The structural elements 23 which are illustrated in FIG. 2b) and which are circular when viewed from above preferably have a diameter of from at least 0.02 mm to a maximum of 2 mm.

[0077] Furthermore, the structural elements 23 preferably have a measured widthperpendicularly to the longitudinal axis L and horizontally in the image plane of FIG. 2of from at least 0.02 mm to a maximum of 2 mm. The width extends in this instance in particular perpendicularly to a main flow direction of the gas flow at the inner side 5 during a compression cycle of the internal combustion engine 2.

[0078] The structural elements 23 preferably have a lengthin the longitudinal direction or along a projection of the longitudinal direction L when looking toward the surface 3which extends in FIG. 2 in the image plane in a vertical direction which is from at least 0.04 mm to a maximum of 4 mm. In this instance, the length extends substantially in the direction of a main flow direction of the gas flow at the inner side 5 during a compression cycle of the internal combustion engine 2.

[0079] The drop-like structural elements 23 according to FIG. 2g) preferably have a corner radius or radius of curvature in the corners of from at least 0.01 mm to a maximum of 1 mm.

[0080] On the whole, it has been found that with the prechamber 1 and the internal combustion engine 2 and using the method there can be provided a structure or geometry for a prechamber which leads to a reduction of the typical fluctuations of a flow pattern inside the prechamber so that cyclical fluctuations in the ignition and thereby in the combustion of the internal combustion engine 2 are also reduced. This increases the combustion stability in general and may in particular be used technically at otherwise unstable operating locations. At the same time, the increased combustion stability can be used indirectly for an increase of the degree of efficiency and for emission reductionwith particular regard to hydrocarbon emissionsof the combustion cycle.