CN113330208A

CN113330208A - Cylinder head of internal combustion engine

Info

Publication number: CN113330208A
Application number: CN202080010205.1A
Authority: CN
Inventors: A·普什尼克; C·诺马耶; A·泽尔克; M·克拉姆普菲尔
Original assignee: AVL List GmbH
Current assignee: AVL List GmbH
Priority date: 2019-01-22
Filing date: 2020-01-22
Publication date: 2021-08-31
Also published as: WO2020150758A1; AT522050A1; AT522053A1; AT522053B1; DE112020000476A5; AT522050B1; DE112020000478A5

Abstract

The invention relates to a cylinder head (1) of an internal combustion engine, in particular a gas engine, comprising: at least one spark plug (8) having at least one ground electrode (10) to form an ignition spark (11); and a prechamber part (2) which accommodates a spark plug (8) and forms a prechamber (5), to which a fuel channel (12) arranged in the prechamber (2) leads. The problem addressed by the invention is to improve ignition. The cylinder head described above solves this problem by orienting the flow axis (S) of the fuel passage (12) at the outlet (13) in the direction of the ground electrode (10) so that substantially the entire fuel flow (B) flows towards the ground electrode (10), the axis of rotation (D) of the spark plug (8) being offset (x) from the axis (a) of the pre-chamber (5), the offset (x) being between 0 and 15% of the maximum pre-chamber diameter (g).

Description

Cylinder head of internal combustion engine

Technical Field

The invention relates to a cylinder head of an internal combustion engine, in particular a gas engine, comprising at least one spark plug having at least one ground electrode for forming an ignition spark and a prechamber part which accommodates the spark plug and forms a prechamber, into which a fuel passage opens, the axis of fuel flow at the outlet of the fuel passage being oriented in the direction of the ground electrode, so that substantially the entire fuel flow flows towards the ground electrode.

Furthermore, the invention relates to a method for manufacturing such a cylinder head and an internal combustion engine with such a cylinder head.

Background

Internal combustion engines and thus cylinder heads are typically liquid cooled.

Spark plugs with prechambers are known, for example, from EP 2894313 a1 for gas four-stroke engines (Otto engines). A fuel valve is provided in a sleeve surrounding the spark plug. The sleeve contains an aperture that extends from the fuel valve to the prechamber. The hole is arranged at an angle to the axis of the spark plug. In this spark plug, for better mixing, guide elements are provided between the spark plug and the fuel valve and the prechamber. The combustion chamber of the internal combustion engine is in flow connection with the prechamber via the transfer port. In this particular arrangement, a standpipe is provided between the prechamber and the transfer port. A disadvantage of this arrangement is that, on the one hand, additional guide elements have to be provided to ensure good mixing. In addition, the distribution of the fuel flow results in undesirable flow conditions.

The flow rate is more difficult to predict due to the distribution of fuel by the conductive element. Therefore, when the ignition spark is generated, the ignitable mixture may be moved away from the ground electrode, resulting in phenomena of retarded ignition, knocking, uneven combustion, and the like. This effect is further exacerbated by the phenomenon of wear.

Disclosure of Invention

The object of the invention is to improve the ignition.

This object is solved by a cylinder head as described above, wherein the axis of rotation of the spark plug is offset from the axis of the prechamber, wherein the offset is between 0% and 15% of the maximum diameter of the prechamber.

The flow axis here refers to a line connecting the diametrical centers of the fuel passages to each other. The direction of the flow axis ignores any unexpected flow effects due to the flow downstream of the fuel valve or fuel channel, corresponding approximately to an undisturbed flow direction at the center of the flow channel.

In view of the general desire in the automotive industry to reduce the size of components, it is advantageous if the flow axis of the fuel channel is curved in at least one direction. Such curvature may reduce the inclination of the fuel valve relative to the prechamber axis without having to deal with disruptive flow effects.

By reducing the inclination in this way, the radial dimension around the prechamber axis can be reduced. The reduced size minimizes weight, which in turn results in a reduction in fuel requirements, which in turn is environmentally friendly. Packaging problems in vehicles are also simplified by the reduction in size. Furthermore, the curvature may cause a tumble or a swirl, which has a positive effect on the mixing in the prechamber.

The targeted flow to the ground electrode allows the ignitable mixture to be delivered more quickly to the vicinity of the ignition spark. This allows for faster and more controlled ignition of the prechamber. The combustion is more uniform and the tendency for knocking in the prechamber is also reduced.

It is further provided that the axis of rotation of the spark plug is offset from the axis of the prechamber, wherein the offset is 0% to 15% of the maximum diameter of the prechamber. This further improves the quality of the combustion, the gas-air mixture being ignited as uniformly and rapidly as possible. A further advantage achieved thereby is that the installation space available in the cylinder head is utilized as efficiently as possible. The targeted flow to the ground electrode and spark plug is combined with a small offset from the prechamber axis, thus further enhancing the advantages described above.

If the offset is 0% or almost 0%, there is no offset between the axis of rotation of the spark plug and the axis of the prechamber, i.e. the two axes merge substantially without offset.

This object is also solved by an internal combustion engine having a cylinder head according to the invention and a method of manufacturing a cylinder head according to the invention.

It is advantageous if the offset between the axis of rotation of the spark plug and the axis of the prechamber is between 0% and 15%, in particular between 0% and 10%, preferably between 0% and 8%, particularly preferably less than 7% of the maximum diameter of the prechamber. This results in a further improvement of the quality of ignition and combustion. Thus, the spark plug is arranged in the center.

It is advantageous if the axis of rotation of the spark plug and the flow axis of the fuel passage lie substantially in one plane and the flow axis is curved substantially in this plane. Thus, flipping may be achieved. This is useful in manufacturing if the fuel channel has curvature in only one plane, as it is thus simplified.

In the context of the present invention, the phrase "substantially" refers to a small amount of deviation in the size and shape of the article of interest from the exact shape or size, e.g., deviation within manufacturing tolerances, as may not be possible to achieve accurately.

Particularly advantageous flow conditions are obtained when the curvature of the fuel channels encloses an angle of between 80 ° and 160 °. This also has benefits in the placement of the fuel valve. Therefore, the installation space can be further reduced.

In an advantageous embodiment, the flow axis provided at the outlet area is arranged substantially perpendicular to the axis of the prechamber, such that the incident flow of the ignition spark is substantially perpendicular to the axis of the prechamber. This is advantageous for a certain installation space.

On the other hand, in alternative embodiments, for other spatial conditions or installation spaces, the flow axis defining the outlet region is substantially angularly inclined with respect to a normal plane through the prechamber axis, such that the incident flow of the ignition spark is substantially angularly inclined with respect to a normal plane through the prechamber axis, wherein the angle is between 0 and 30 °.

In order to shorten the distance between the ground electrode and the fuel passage, it is advantageous if the outlet of the fuel passage is arranged along the axis of the prechamber in a horizontal line with the ground electrode.

It is advantageous if the prechamber part has a prechamber housing for forming a prechamber and a sleeve surrounding the spark plug, wherein the prechamber housing and the sleeve are each formed integrally with one another and/or are connected to one another. In this way, the prechamber parts can be easily removed from the cylinder head when ignition problems occur, making repair and replacement easier and less costly. If the prechamber housing and the sleeve are interconnected, this can be achieved by means of a screw connection with a seal, for example. Thus, it may be provided that the sleeve is integrally formed and the prechamber housing is integrally formed and then connected together. However, it is also possible that the sleeve and the prechamber sleeve together form a single piece.

In a special embodiment provision is made for a fuel valve to be arranged in the prechamber part. In this way, leakage can be successfully avoided.

In order to achieve an advantageous flow in the fuel passage, provision is made in an advantageous embodiment for the flow axis of the fuel passage to substantially correspond to the axis of rotation of the fuel valve in the region of the fuel passage adjoining the fuel valve. Thus, turbulence downstream of the fuel valve can be avoided. However, it may also be provided that the axis of rotation of the fuel valve is not coaxial with the axis of the fuel channel 12, but that an angle of about 0 ° to about 0 ° is provided between the two axes.

It is advantageous if the fuel valve is arranged inclined with respect to the axis of the prechamber, wherein the inclination preferably corresponds to an angle of between-10 ° and +35 °. By reducing the above-mentioned inclination, an inclination of 0 °, i.e. no inclination, can be provided in the extreme case. This does result in the greatest savings in space. However, the flow in the first region of the fuel channel adjacent to the fuel valve will need to be bent or deflected, so that the flow may be negatively affected.

This effect is further increased when the offset is in a plane and the ground electrode is positioned away from the fuel passage due to the offset relative to the prechamber axis.

In order to obtain maximum flexibility in the arrangement of the components, it is envisaged that the axis of rotation of the spark plug is at an angle to the axis of the prechamber, this angle being between 0 ° and 30 °.

For the tightness and robustness of the invention it is advantageous if the fuel channel is formed by a tubular recess in the prechamber part along the flow axis, such that the recess of the fuel channel is radially surrounded around the flow axis by the material of the prechamber part.

In order to facilitate production, in an advantageous variant of the method it is provided that the spark plug thread for the spark plug in the prechamber part is cut such that after the screwing-in process, the ground electrode is arranged in a defined position relative to the fuel passage. In principle, it is advantageous if the cylinder head is at least partly produced via 3D printing, in particular a pre-chamber and/or a spark plug. In particular, at least a portion of the cylinder head is produced by a laser-melted additive manufacturing process.

Drawings

The invention is explained in further detail with reference to non-limiting exemplary embodiments in the drawings, in which:

FIG. 1 shows a detail view in cross-section of a cylinder head according to the invention in a first embodiment;

FIG. 2 shows an enlarged view of a detail in FIG. 1;

FIG. 3 shows an alternative enlarged view from FIG. 1;

FIG. 4 shows a detail in cross section of a cylinder head according to the invention in a second embodiment; and

fig. 5 shows a schematic view of a prechamber component of a cylinder head according to the invention with spark plugs and fuel valves in a first embodiment and a third embodiment.

Detailed Description

Fig. 1 shows details of a liquid cooled cylinder head 1 in a first embodiment. Here, the cylinder head 1 is a part of an internal combustion engine that operates as a gas four-stroke engine (Otto engine). The detail view shows the prechamber part 2 in more detail. In the shown embodiment the prechamber part 2 has a sleeve 3 and a prechamber housing 4 connected to the sleeve 3. Here, the prechamber housing 4 has an external thread and the sleeve 3 has an internal thread. The prechamber housing 4 is screwed to the sleeve 3. There is a seal between the prechamber housing 4 and the sleeve 3.

Prechamber housing 4 encloses a large part of prechamber 5, prechamber 5 being flow-connected to combustion chamber 7 via overflow openings 6. The combustion chamber 7 is adjoined by the prechamber element 2 and further by the cylinder head 1 and is substantially closed by it in the direction of the prechamber 5.

A spark plug 8 and a gas valve 9 are arranged inside the sleeve 3. The spark plug 8 extends into the prechamber 5 via a ground electrode 10. The area of the spark plug 8 where the ignition spark is formed is provided with reference numeral 11.

In the first embodiment, the axis of rotation D of the spark plug 8 is aligned parallel to the axis a of the prechamber 5. In the first illustrated embodiment, the axis of rotation D and the axis a are offset. In an alternative embodiment, the axis of rotation D and the axis a are the same.

The fuel valve 9 is arranged along an axis V, which corresponds to the axis of rotation of the fuel valve 9. This axis V is aligned at an angle to the axis a of the prechamber.

According to the invention, the fuel valve 9 is connected to the prechamber 5 via a fuel channel 12. The fuel passage 12 extends along a flow axis S. The flow axis S corresponds in its direction to an undisturbed flow vector in the fuel passage 12.

The fuel passage 12 has an outlet 13 into the prechamber 5. At least at the outlet 13, the fuel passage 12 is oriented in the direction of the ignition spark 11 and the ground electrode 10. Therefore, the fuel flows in the direction of the ignition spark 11 as indicated by the arrow B.

The fuel valve 9 is at a distance a from the prechamber 5. The distance a is the distance from the fuel valve 9 into the fuel passage 12, the inlet of the fuel passage, from the outlet 13 of the fuel passage 12 into the prechamber 5, the delivery point of the fuel.

In the embodiment shown, the maximum prechamber diameter g is reached at the transition to the spark plug 8. In these embodiments, the maximum prechamber diameter g is slightly larger than the diameter of the spark plug 8. In alternative embodiments, these diameters may be the same.

This arrangement is shown in somewhat enlarged form in figure 2. This shows that the axis of rotation D and the axis a of the prechamber 5 are slightly offset x from each other. Thus, the spark plug 8 is further from the fuel valve 9 due to the offset x. In the embodiment shown, the axis V of the fuel valve 9 and the axis of rotation D of the spark plug 8 lie in a plane epsilon, which also forms the section plane of fig. 1 to 5. The image plane is therefore marked as reference plane epsilon. The offset x in fig. 2 is less than 10% of the maximum prechamber diameter g.

The fuel passage 12 has a curvature 12a between an inlet and an outlet 13 which meet the gas valve 9. In this case, the flow axis S is curved in the plane epsilon. In alternative embodiments, the shape of the fuel passage 12 may also be more complex.

For clarity, not all components in fig. 2 are labeled. The missing reference numbers can be taken from fig. 1.

Fig. 3 shows the section of fig. 1 and 2, in which the spark plug 8 with the ground electrode 10 and the ignition spark 11 can be clearly seen.

The gas is discharged into the fuel passage 12 through the fuel valve 9. The fuel passage 12 deflects the fuel flow B substantially along the flow axis S, where it is directed towards the ground electrode 10 at the outlet 13. An ignition spark 11 is generated between the ground electrode 10 and the main portion of the spark plug 8. The gas, i.e. the fuel, is immediately ignited by this flow B in the direction of the ignition spark B.

In this case, the outlet 13 of the fuel passage 12 is arranged with the flow axis S at the level of the ignition spark 11, while the fuel flow B is discharged in the direction of the ignition spark 11 approximately along an unmarked normal plane of the axis a of the prechamber 5.

The curvature 12a thus deflects the flow axis S by an angle δ.

Fig. 4 shows a detail of a second version of a cylinder head 1 according to the invention, similar to that of fig. 3. Hereinafter, only the differences from the first embodiment are explained. Like reference numerals denote parts having the same function.

In contrast to the first embodiment, in the second embodiment the outlets 13 are not arranged at the same height along the axis a of the prechamber 5. In this case, the flow axis S of the outlet 13 is arranged closer to the ignition plug 8 than in the first embodiment.

The flow axis S is inclined by an angle β in the region of the outlet 8. In this case, the fuel flow B is also inclined by the angle β and directed towards the ignition spark 11.

Fig. 5 shows an alternative axis of rotation d of the spark plug 8 in a third embodiment. The axis of rotation d has an inclination a to the axis a of the prechamber.

Furthermore, the figure also shows the angle γ, i.e. the axis V of the fuel valve 9 is angled to a straight line parallel to the axis a of the prechamber. The fuel valve 9 is inclined at an angle gamma with respect to the straight line.

The cylinder head 1 is liquid cooled. As can be seen from fig. 1 and 2, the cooling chamber adjoins the prechamber part 2. This may protect the surroundings of the spark plug 8, the prechamber part 2 and the cylinder head 2 from heat damage and allow heat dissipation.

Claims

1. Cylinder head (1) of an internal combustion engine, in particular a gas engine, comprising: at least one spark plug (8) having at least one ground electrode (10) for forming an ignition spark (11); -a pre-chamber part (2) accommodating the spark plug (8) and forming a pre-chamber (5), -a fuel passage (12) arranged in the pre-chamber part (2) opening into the pre-chamber (5), wherein a flow axis (S) of the fuel passage (12) is oriented at an outlet (13) in the direction of the ground electrode (10) such that substantially the entire fuel flow (B) flows towards the ground electrode (10), characterized in that the rotation axis (D) of the spark plug (8) has an offset (x) with respect to the axis (a) of the pre-chamber (5), wherein the offset (x) is between 0 and 15% of the maximum pre-chamber diameter (g).

2. Cylinder head (1) according to claim 1, characterized in that the offset between the axis of rotation (D) of the spark plug (8) and the axis (a) of the prechamber (5) is between 0% and 15%, in particular between 0% and 10%, preferably between 0% and 8%, particularly preferably less than 7% of the prechamber maximum diameter (g).

3. Cylinder head (1) according to claim 1 or 2, characterized in that the flow axis (S) of the fuel channel (12) is curved in at least one direction.

4. A cylinder head (1) according to claim 3, characterized in that the axis of rotation (D) of the spark plug (8) and the flow axis (S) of the fuel channel (12) substantially lie in one plane (epsilon), and wherein the flow axis (S) is substantially curved in said plane (epsilon).

5. Cylinder head (1) according to claim 3 or 4, characterized in that the curvature (12a) of the fuel channel (12) encloses an angle (δ) between 80 ° and 160 °.

6. Cylinder head (1) according to one of claims 1 to 5, characterized in that the flow axis (S) in the region of the outlet (13) is arranged substantially perpendicular to the axis (A) of the prechamber (5) so that the incident flow of the ignition spark (11) is substantially perpendicular to the axis (A) of the prechamber (5).

7. Cylinder head (1) according to one of claims 1 to 5, characterized in that the flow axis (S) in the region of the outlet (13) is inclined substantially at an angle (β) with respect to a normal plane through the axis (A) of the prechamber (5), such that the incident flow of the ignition spark (11) is inclined substantially at said angle (β) with respect to a normal plane through the prechamber axis (A), wherein the angle (β) is between 0 ° and 30 °.

8. Cylinder head (1) according to one of claims 1 to 7, characterized in that the outlet (13) of the fuel passage (12) is arranged with the flow axis (S) at the level of the ground electrode (10) along the axis (A) of the prechamber (5).

9. Cylinder head (1) according to one of claims 1 to 8, wherein the prechamber part (2) comprises a prechamber housing (4) for forming the prechamber (5) and a sleeve (3) surrounding the spark plug (8), wherein the prechamber housing (4) and the sleeve (3) are integral with each other and/or connected to each other.

10. Cylinder head (1) according to one of claims 1 to 9, characterized in that a fuel valve (9) is arranged in the prechamber part (2).

11. Cylinder head (1) according to claim 10, characterized in that the flow axis (S) of the fuel channel (12) substantially corresponds to the rotation axis (V) of the fuel valve in the area where the fuel channel (12) adjoins the fuel valve (9).

12. Cylinder head (1) according to one of claims 10 or 11, characterized in that the fuel valve (9) is arranged inclined with respect to a line parallel to the axis (a) of the prechamber, wherein the inclination preferably corresponds to an angle (γ) of between-10 ° and +35 °.

13. Cylinder head (1) according to one of claims 1 to 12, characterized in that the offset (x) lies in a plane (epsilon) and the ground electrode (10) is arranged facing away from the fuel passage (12) with the offset (x) relative to the axis (a) of the prechamber (5).

14. Cylinder head (1) according to one of claims 1 to 13, characterized in that the axis of rotation (D) of the spark plug (8) has an angle (a) of between 0 ° and 30 ° with respect to the axis (a) of the prechamber (5).

15. Cylinder head (1) according to one of claims 1 to 14, characterized in that the fuel passage (12) is formed by a tubular recess in the prechamber part (2) along the flow axis (S) such that the recess of the fuel passage (12) is radially surrounded around the flow axis (S) by the material of the prechamber part (2).

16. Internal combustion engine having a cylinder head (1) according to any one of claims 1 to 15.

17. Method for manufacturing a cylinder head (1) according to one of the claims 1 to 15, characterized in that the cylinder head (1) is at least partially manufactured by 3D printing.

18. Method according to claim 17, characterized in that a spark plug thread for the spark plug (8) in the prechamber part (2) is cut such that the ground electrode (10) is arranged in a defined position relative to the fuel channel (12) after the screwing process.