PRE-CHAMBER AND METHOD FOR PRODUCING A PRE-CHAMBER

Abstract

Pre-chamber for an internal combustion engine, preferably gas engine, comprising: a pre-chamber body; a pre-chamber volume which is surrounded by the pre-chamber body; and a pre-chamber tip portion comprising at least two, preferably more than two, spray nozzles, wherein the at least two spray nozzles are in fluid communication with the pre-chamber volume, and the pre-chamber tip portion is affixed to the pre-chamber body by a welding process or a brazing process;
wherein the pre-chamber body consists of a material with higher thermal conductivity than the pre-chamber tip portion.

Claims

1. A system, comprising: a pre-chamber for an internal combustion engine, comprising: a pre-chamber body; a pre-chamber volume surrounded by the pre-chamber body; and a pre-chamber tip portion comprising at least two spray nozzles, wherein the at least two spray nozzles are in fluid communication with the pre-chamber volume, and the pre-chamber tip portion is affixed to the pre-chamber body by a welded joint or a brazed joint; wherein the pre-chamber body consists of a first material with a higher thermal conductivity than a second material of the pre-chamber tip portion.

2. The system according to claim 1, wherein the first material of the pre-chamber body consists of copper or a copper alloy and/or the second material of the pre-chamber tip portion consists of an alloyed steel having a higher wear resistance than the first material of the pre-chamber body.

3. The system according to claim 1, wherein the first material of the pre-chamber body consists of a copper-nickel alloy and/or the second material of the pre-chamber tip portion consists of alloy 416, or alloy 4140, or alloy HA 282.

4. The system according to claim 1, wherein a tip height (h) of the pre-chamber tip portion is less than 50% of an overall height (H) of the pre-chamber, wherein both the tip height (h) and the overall height (H) are measured along a longitudinal axis (X) of the pre-chamber.

5. The system according to claim 1, wherein the pre-chamber volume and the at least two spray nozzles are in fluid connection via a riser passage, wherein at least a part of the riser passage is disposed in the pre-chamber tip portion.

6. The system according to claim 1, comprising the welded joint having a friction welded joint or an electron-beam welded joint.

7. The system according to claim 1, comprising a cylinder head of the internal combustion engine, wherein the pre-chamber is coupled to the cylinder head, wherein a connecting interface between the pre-chamber body and the pre-chamber tip portion is disposed inside a fire plate of the cylinder head when the pre-chamber is mounted inside the cylinder head.

8. The system according to claim 1, comprising the internal combustion engine having the pre-chamber.

9. A method for producing a pre-chamber comprising: providing a first part and a second part, the first part consisting of a first material with a higher thermal conductivity than a second material of the second part; joining the first part with the second part by a welding process or a brazing process; machining of the first part to form a first outer contour a pre-chamber body of the pre-chamber; machining of the first part to form a first inner contour of a pre-chamber volume and/or at least part of a riser passage of the pre-chamber; machining of the second part to form a second outer contour of a pre-chamber tip portion of the pre-chamber; and machining of the second part to form a second inner contour of at least two spray nozzles and/or at least part of the riser passage.

10. The method according to claim 9, wherein machining the first outer contour and/or the first inner contour and/or the second outer contour and/or the second inner contour is performed after joining a first machined front face of the first part with a second machined front face of the second part.

11. The method according to claim 9, wherein machining the first outer contour and/or the first inner contour and/or the second outer contour and/or the second inner contour is performed before joining a first machined front face of the first part with a second machined front face of the second part.

12. The method according to claim 9, wherein joining the first part with the second part comprises a friction welding process or an electron-beam welding process as the welding process for joining a first machined front face of the first part with a second machined front face of the second part.

13. The method according to claim 9, comprising rounding of inner edges, including a transition between the riser passage and the at least two spray nozzles.

14. The method according to claim 9, wherein the following steps are performed: before the first part and the second part are joined machining of a first front face of the first part to obtain a first machined front face and of a second front face of the second part to obtain a second machined front face, and joining the first machined front face of the first part with the second machined front face of the second part by the welding process or the brazing process.

15. A system, comprising: a pre-chamber for an internal combustion engine, comprising: a pre-chamber body; a pre-chamber volume surrounded by the pre-chamber body; and a pre-chamber tip portion comprising one or more fluid nozzles, wherein the one or more fluid nozzles are in fluid communication with the pre-chamber volume, and the pre-chamber tip portion is coupled to the pre-chamber body; wherein the pre-chamber body comprises a first material with a higher thermal conductivity than a second material of the pre-chamber tip portion.

16. The system according to claim 15, comprising a cylinder head and/or the internal combustion engine having the pre-chamber.

17. The system according to claim 15, wherein the second material of the pre-chamber tip portion has a higher wear resistance than the first material of the pre-chamber body.

18. The system according to claim 15, wherein the first material of the pre-chamber body comprises copper or a copper alloy and the second material of the pre-chamber tip portion comprises an alloyed steel.

19. The system according to claim 15, wherein the first material of the pre-chamber body comprises a copper-nickel alloy and the second material of the pre-chamber tip portion comprises an alloy 416, or alloy 4140, or alloy HA 282.

20. The system according to claim 19, wherein the copper-nickel alloy comprises CuNi.sub.3Si and/or CuNi.sub.2Si.

Description

BRIEF DESCRIPTION OF THE DRAWINGS

[0054] Further details and advantages of the invention are apparent from the figures and the accompanying description of the figures. The figures show:

[0055] FIG. 1 is a cross-section of an embodiment of a pre-chamber according to aspects of the invention,

[0056] FIG. 2 is a perspective view of the embodiment of FIG. 1,

[0057] FIGS. 3 and 4 illustrate a comparison of the temperatures inside a pre-chamber according to the prior art and a pre-chamber according to aspects of the invention,

[0058] FIGS. 5 and 6 illustrate a comparison of the mechanical stresses inside a pre-chamber according to the prior art and a pre-chamber according to aspects of the invention,

[0059] FIGS. 7 and 8 illustrate two steps during an embodiment of the production method according to aspects of the invention, and

[0060] FIG. 9 is an embodiment of the internal combustion engine according to aspects of the invention.

DETAILED DESCRIPTION

[0061] FIGS. 1 and 2 show an embodiment of the pre-chamber 1 according to aspects of the invention. The pre-chamber 1 comprises a pre-chamber body 2, which encloses the pre-chamber volume 3.

[0062] The pre-chamber tip portion 4 is affixed to the pre-chamber body 2, in this case through a welding process attaching the pre-chamber tip portion 4 to the pre-chamber body 2 at the interface 6.

[0063] The tip portion 4 includes in this example eight spray nozzles 5.

[0064] In this embodiment, the pre-chamber volume 3 is in fluid communication with the spray nozzles 5 through a riser passage 7.

[0065] If an air fuel mixture is ignited in the pre-chamber volume 3, the resulting combusting mixture will travel from the pre-chamber volume 3 down the riser passage 7 and through the spray nozzles 5. The combusting mixture will then form flame jets extending into the main combustion chamber, where a potentially very lean (high lambda) air fuel mixture can be ignited thoroughly and swiftly.

[0066] FIGS. 3 and 4 show a comparison of the temperatures inside a pre-chamber 1 according to the prior art and a pre-chamber according to aspects of the invention (FIG. 3: prior art, FIG. 4: according to aspects of the invention). The embodiment according to the prior art is a monolithic pre-chamber 1.

[0067] Evidently, the pre-chamber 1 according to the prior art overall exhibits much higher temperatures, especially at the tip portion. Here, the advantage of aspects of the invention can be seen plainly. The pre-chamber tip portion 4 according to aspects of the invention experiences much lower temperatures, even though it can still be made from a material with very high thermal resistance. At the same time, the effort for manufacturing the pre-chamber 1 according to aspects of the invention is only increased marginally compared to the pre-chamber 1 of FIG. 1, and the effort for manufacturing according to aspects of the invention is massively smaller compared to pre-chambers 1 as disclosed in US 2013/0139784 A1.

[0068] Surprisingly, aspects of the invention can also decrease and shift the location of the maximum of mechanical stress present in the pre-chamber 1 during operation, even though there is a welded or brazed joint present. FIGS. 5 and 6 are a comparison between the mechanical stresses in a monolithic pre-chamber 1 according to the prior art (FIG. 5) and according to aspects of the invention (FIG. 6).

[0069] Even though there is a slight increase in mechanical stress near the welded joint, the stress near the bridges between the openings for the spray nozzles 5 experience a lower mechanical stress. It should be pointed out that the areas between the openings for the spray nozzles 5 experience the highest mechanical and thermal loads in the pre-chamber 1, so that a reduction of stress in this area is far more important than the slight increase of the stress near the joint.

[0070] The reduction of mechanical stress according to aspects of the invention originates from at least the following two reasons: [0071] reduced temperature level in the pre-chamber tip portion; [0072] initiated residual stresses in the joint (due to different thermal expansion of the welded or brazed material), which reduce maximum stresses and shift the locations of maximum stresses in critical areas.

[0073] FIGS. 3 to 6 are grey scale depictions where darker shades of grey signify higher temperatures/stresses, and lighter shades of grey signify lower temperatures/stresses.

[0074] FIGS. 7 and 8 show intermediary steps in an embodiment of the production/manufacturing method according to aspects of the invention.

[0075] In this embodiment, initially a first part 8 and a second part 9, both in the form of bar stock, are provided (FIG. 7). The first part 8 and the second part 9 may both include machined front faces 11a and 11b, respectively.

[0076] The first part 8 and the second part 9 are then joined by a welding process at the interface 6 (FIG. 8).

[0077] Subsequently, the first part 8 and the second part 9 can be machined to yield the first outer contour 12, the first inner contour 13, the second outer contour 14, and the second inner contour 15 as depicted in FIG. 1.

[0078] The at least two spray nozzles 5 can additionally or alternatively be manufactured as bores, and inner edges can be rounded afterwards.

[0079] Alternatively, the embodiment of FIG. 1 can be manufactured by first machining the first part 8 and the second part 9 creating the first outer contour 12, the first inner contour 13, the second outer contour 14, and the second inner contour 15, and then the first part 8/pre-chamber body 2 and the second part 9/pre-chamber tip portion 4 can be joined.

[0080] Mixed embodiments where some of the contours (e.g., the first outer contour 12, the first inner contour 13, the second outer contour 14, and the second inner contour 15) are machined before the joining of the first part 8 and the second part 9 and other contours can be machined afterwards.

[0081] FIG. 9 shows an embodiment of an internal combustion engine 10 in the vicinity of the cylinder head 20.

[0082] The pre-chamber 1 is arranged inside the cylinder head 20. In the arrangement of the cylinder head 20 and the pre-chamber 1, the relative position is such that the interface 6 between the pre-chamber body 2 and the pre-chamber tip portion 4 is disposed inside the fire plate 16.