CYLINDER HEAD FOR AN INTERNAL COMBUSTION ENGINE

Abstract

A cylinder head for an internal combustion engine comprising a prechamber (3), wherein a prechamber gas valve (5) is fitted into a cavity of the cylinder head (2) and the prechamber gas valve (5) is connected to the prechamber (3) by way of a flow transfer passage (10), wherein the flow transfer passage (10) for a given cross-sectional area immediately downstream of the prechamber gas valve (5) is of such a length that in operation of the cylinder head (2) mounted in an internal combustion engine in a compression stroke of the combustion process propellant gas which flow out of the prechamber gas valve (5) forms a gas cushion at least in a first portion (8) of the flow transfer passage (10), that adjoins the prechamber gas valve (5).

Claims

1. A system, comprising: a cylinder head for an internal combustion engine comprising a prechamber, wherein a prechamber gas valve is fitted into a cavity of the cylinder head and the prechamber gas valve is connected to the prechamber by way of a flow transfer passage, wherein the flow transfer passage for a given cross-sectional area immediately downstream of the prechamber gas valve is of such a length that in operation of the cylinder head mounted in the internal combustion engine in a compression stroke of a combustion processes, propellant gas flows out of the prechamber gas valve and forms a gas cushion at least in a first portion of the flow transfer passage, wherein the first portion adjoins the prechamber gas valve.

2. The system of claim 1, wherein the flow transfer passage with respect to the cross-sectional area immediately downstream of the prechamber gas valve is of an equivalent length of about 15 to about 23 mm.

3. The system of claim 1, wherein the flow transfer passage further has a second portion into which the first portion (8) opens, wherein the second portion extends at least around a part of a periphery of the prechamber, wherein the second portion has an uninterrupted peripheral surface apart from an opening between the second portion and the prechamber.

4. The system of claim 1, wherein the cylinder head comprises a spark plug disposed in a spark plug sleeve.

5. The system of claim 1, wherein the second portion extends in an angular range (α) of about 20° to about 270°.

6. The system of claim 1, wherein a cross-sectional area of the flow transfer passage, at least over a length of the first portion, is between about 1.Math.π mm.sup.2 and about 2.5.sup.2.Math.π mm.sup.2.

7. The system of claim 1, wherein a total length of the flow transfer passage is between about 30 mm and about 70 mm.

8. The system of claim 1, wherein at least the second portion of the flow transfer passage is disposed between a first surface of the prechamber and a second surface of the cylinder head.

9. The system of claim 6, wherein at least the second portion of the flow transfer passage comprises at least one groove in the first surface or the second surface.

10. The system of claim 1, wherein the second portion of the flow transfer passage has a substantially parallel portion in relation to a separation plane between the prechamber and the cylinder head.

11. The system of claim 1, wherein the first portion of the flow transfer passage has a portion inclined substantially relative to a separation plane between the prechamber and the cylinder head.

12. The system of claim 1, wherein a space is provided between a seat of a valve head of the prechamber gas valve and a mouth opening of the prechamber gas valve into the flow transfer passage.

13. The system of claim 1, wherein the flow transfer passage is of a cross-section varying over its length.

14. The system of claim 1, comprising the internal combustion engine having the cylinder head.

15. A method, comprising: forming a flow transfer passage in a portion of a cylinder head of an internal combustion engine, wherein the flow transfer passage is disposed between a prechamber gas valve and a prechamber space of a prechamber, wherein the flow transfer passage is configured to flow a propellant gas from the prechamber gas valve to the prechamber space during an operation of the cylinder head mounted in the internal combustion engine in a compression stroke of a combustion process, wherein a length and a cross-sectional area of the flow transfer passage downstream of the prechamber gas valve is configured such that the propellant gas forms a gas cushion during the operation of the cylinder head.

16. The method of claim 15, wherein the flow transfer passage with respect to the cross-sectional area downstream of the prechamber gas valve is of an equivalent length of about 15 to about 23 mm.

17. The method of claim 15, wherein the cross-sectional area of the flow transfer passage is between about 1.Math.π mm.sup.2 and about 2.5.sup.2.Math.π mm.sup.2.

18. A system, comprising: at least a portion of a cylinder head of an internal combustion engine, wherein the portion comprises a flow transfer passage disposed between a prechamber gas valve and a prechamber space of a prechamber, wherein the flow transfer passage is configured to flow a propellant gas from the prechamber gas valve to the prechamber space during an operation of the cylinder head mounted in the internal combustion engine in a compression stroke of a combustion process, wherein a length and a cross-sectional area of the flow transfer passage downstream of the prechamber gas valve is configured such that the propellant gas forms a gas cushion during the operation of the cylinder head.

19. The system of claim 18, wherein the flow transfer passage with respect to the cross-sectional area downstream of the prechamber gas valve is of an equivalent length of about 15 to about 23 mm.

20. The system of claim 18, wherein the cross-sectional area of the flow transfer passage is between about 1.Math.π mm.sup.2 and about 2.5.sup.2.Math.π mm.sup.2.

Description

BRIEF DESCRIPTION OF THE DRAWINGS

[0033] Embodiments of the invention are described with reference to the drawings in which:

[0034] FIG. 1 shows a first embodiment of a cylinder head,

[0035] FIG. 2 shows the cross-section indicated in FIG. 1,

[0036] FIG. 3 shows a second embodiment of a cylinder head,

[0037] FIG. 4 shows the cross-section indicated in FIG. 3,

[0038] FIG. 5 shows an alternative embodiment to FIG. 4,

[0039] FIG. 6 shows a further alternative embodiment to FIG. 4,

[0040] FIG. 7 shows a third embodiment of a cylinder head,

[0041] FIG. 8 shows a fourth embodiment of a cylinder head, and

[0042] FIG. 9 shows a fifth embodiment of a cylinder head.

DETAILED DESCRIPTION

[0043] FIGS. 1 and 2 show a first embodiment of a cylinder head 2 for an internal combustion engine having a prechamber 3. The prechamber gas valve 5 and a spark plug (not shown for reasons of clarity) are fitted in a spark plug sleeve 4. In the installation position, the spark plug sleeve 4 is fitted into the cylinder head 2 of the internal combustion engine (not shown here in its entirety).

[0044] FIG. 1 shows a longitudinal section through the cavity of the cylinder head 2 into which the spark plug sleeve 4 is fitted. The spark plug sleeve 4 includes a shaft which is concentric around the axis of symmetry S1 and comprises cylindrical portions for receiving a spark plug and it has a bore with the axis of symmetry S2 for receiving a prechamber gas valve 5.

[0045] A flow transfer passage 10 leads from the prechamber gas valve 5 to the prechamber 3. The prechamber 3 comprises the actual prechamber space 6, that is to say a hollow space in which the ignition of mixture takes place and the flow transfer bores 9, through which the prechamber space 6 is connected to the main combustion chamber (not shown). After ignition in the prechamber space 6, the ignition flares pass into the main combustion chamber by way of the flow transfer bores 9. In the present embodiment, the prechamber 3 is in the form of a component separate from the spark plug sleeve 4 and is connected, for example pressed, to the spark plug sleeve 4.

[0046] The spark plug 6 (not shown for the sake of clarity) is screwed into the spark plug sleeve 4 by way of the spark plug bore 12, which is concentric with the axis of symmetry S1, in such a way that it preferably terminates flush with the prechamber 3 and its electrode or electrodes project into the prechamber 3. The prechamber 3 is enriched with propellant gas by the prechamber gas valve 5 by way of the flow transfer passage 10.

[0047] It can be clearly seen here how the flow transfer passage 10 is subdivided into a first portion 8 and a second portion 1. The first portion 8 leads from a space 11, which is arranged at the prechamber gas valve 5 and has a closed peripheral surface to the second portion 1 into which the first portion 8 transitions. The first portion 8 in that case is in the form of a bore in the spark plug sleeve 4, which is inclined at an angle β relative to the axis of symmetry S2 or also the axis of symmetry of the valve body.

[0048] FIG. 2 shows the section A-A indicated in FIG. 1 through the separation plane between the prechamber 3 and the spark plug sleeve 4. That section makes it possible to see the second portion 1 of the flow transfer passage 10, which extends in an angular range α around a part of a periphery of the prechamber 3, wherein the second portion 1 (apart from that opening 7 with which it opens into the prechamber space 6) has an uninterrupted peripheral surface. For the sake of clarity, the cylinder head 2 is not shown in this Figure. In this embodiment, the second portion 1 of the flow transfer passage 10 is provided by a milled groove in the spark plug sleeve 4, which is closed by the adjoining wall of the prechamber 3 and forms a passage (second portion 1 of the flow transfer passage 10).

[0049] FIGS. 3 and 4 show a second embodiment of a cylinder head 2 for an internal combustion engine. Unlike FIGS. 1 and 2, in the embodiment of FIGS. 3 and 4 the second portion 1 of the flow transfer passage 10 is provided in the prechamber 3. That is particularly clear from FIG. 3. FIG. 4 in turn shows the section B-B indicated in FIG. 3 through the separation plane between the prechamber 3 and the spark plug sleeve 4.

[0050] In FIGS. 3 and 4, the second portion 1 of the flow transfer passage 10 extends in an angular range α around a part of a periphery of the prechamber 3, wherein the second portion 1 (apart from that opening 7 with which it opens into the prechamber space 6) has an uninterrupted peripheral surface. In this embodiment, the second portion 1 of the flow transfer passage 10 is provided by a milled groove in the prechamber 3, that is closed by the adjoining wall of the spark plug sleeve 4 and forms a passage (second portion 1 of the flow transfer passage 10).

[0051] FIGS. 5 and 6 show alternative embodiments of the second portion 1 of the flow transfer passage 10 in the same cross-section B-B as also shown by FIG. 4, that cross-section being defined by FIG. 3. These embodiments, however, can also be designed analogously in relation to the embodiment shown in FIG. 1.

[0052] FIG. 5 shows an embodiment in which the second portion 1 of the flow transfer passage 10 opens tangentially into the periphery of the prechamber space 6 with the opening 7. By virtue of the variation in the entry angle of the flow transfer passage 10, more precisely its second portion 1, into the prechamber space 6, it is possible to closed-loop/open-loop control flooding of the prechamber 3 by the propellant gas. The second portion 1 of the flow transfer passage 10 is formed by a milled groove in the prechamber 3.

[0053] The embodiment shown in FIG. 6 has a second portion 1 of the flow transfer passage 10, that has a cross-sectional narrowing 13 before the opening 7 into the prechamber space 6. By virtue of the variation in the cross-section of the flow transfer passage 10, more precisely its second portion 1, upstream of the prechamber space 6, it is possible to closed-loop/open-loop control the speed at which the propellant gas flows in. The second portion 1 of the flow transfer passage 10 is again provided by a milled groove in the prechamber 3.

[0054] FIG. 7 shows a third embodiment of a cylinder head 2 having a prechamber 3. In the example shown in FIG. 7, however, the prechamber 3 is connected directly to the cylinder head 2 (for example by way of a press fit) without the provision of a spark plug sleeve 4. The flow transfer passage 10 between the prechamber gas valve 5 and the prechamber space 6 has a first portion 8 and a second portion 1. The first portion 8 is provided by a bore in the cylinder head 2, which bore is inclined at an angle β relative to the axis of symmetry S2 and passes the propellant gas out of the space 11 into the second portion 1 of the flow transfer passage 10. The second portion 1 is formed by a straight milled groove in the cylinder head 2, which in combination with the adjoining wall of the prechamber 3, forms a passage.

[0055] FIG. 8 shows a fourth embodiment of a cylinder head 2 having a prechamber 3. Unlike the preceding Figures, the first portion 8 of the flow transfer passage 10 is formed by a perpendicular bore in the cylinder head 2, which extends concentrically relative to the axis of symmetry S2 of the prechamber gas valve 5 and the space 11. Adjoining the first portion 8 of the flow transfer passage 10, there follows the second portion 1 formed by an inclined bore and a groove milled in the cylinder head 2.

[0056] The embodiment shown in FIG. 9 only has a continuous connecting bore between prechamber space 6 and the space 11 of the prechamber gas valve 5, representing the flow transfer passage with its first portion 8 and its second portion 1. This embodiment takes up a relatively large amount of space in comparison with the previously described embodiments and is, therefore, only to be used in situations involving a generous amount of space.

LIST OF REFERENCES

[0057] 1 second portion [0058] 2 cylinder head [0059] 3 prechamber [0060] 4 spark plug sleeve [0061] 5 prechamber gas valve [0062] 6 prechamber space [0063] 7 opening [0064] 8 first portion [0065] 9 connecting passage [0066] 10 flow transfer bores [0067] 11 space [0068] 12 spark plug bore [0069] 13 cross-sectional narrowing [0070] S1 axis of symmetry [0071] S2 axis of symmetry [0072] α angular range [0073] β angle