COMBUSTION ENGINE FOR A MOTOR VEHICLE

Description

[0001] The invention relates to an internal combustion engine for a motor vehicle, in particular for a car, according to the preamble of claim 1. Such an internal combustion engine for a motor vehicle, in particular for a car, is known, for example, from DE 10 2021 000 690 A1 or from DE 10 2016 105673. The internal combustion engine has at least one combustion chamber and at least one cylinder head, which has at least one combustion chamber roof that partially delimits the combustion chamber. Two exhaust ports of the cylinder head and, in particular, a spark plug held on the cylinder head, which is arranged at least partially between the exhaust ports, are associated with the combustion chamber roof and thus with the combustion chamber.

[0002] The object of the present invention is to further develop an internal combustion engine of the type mentioned above in such a way that particularly efficient operation can be achieved.

[0003] This problem is solved by an internal combustion engine with the features of claim 1. Advantageous embodiments with expedient further developments of the invention are specified in the remaining claims. In order to further develop an internal combustion engine of the type specified in the preamble of claim 1 in such a way that particularly efficient operation of the internal combustion engine can be achieved, a cylindrical indentation is provided in each exhaust port on the respective side of the exhaust port facing the spark plug, according to the invention. The invention is based in particular on the following findings and considerations: The airflow through the respective exhaust port, also referred to as the exhaust port flow rate, is crucial for the performance of an internal combustion engine, also referred to as a combustion engine or internal combustion power unit.For this, the design of the respective exhaust port, also known as the exhaust channel, is crucial. However, the exhaust port design is typically subject to the following limitations: The spark plug is advantageously positioned between the exhaust ports and thus between the exhaust valves associated with them. However, this can significantly reduce the airflow cross-section of each exhaust port. Advantageously, the spark plug is cooled by a water jacket between a spark plug well, in which the spark plug is located, and the respective exhaust port, which can further reduce the flow cross-section.The exhaust ports are typically manufactured using a cast core, which, for example, forms the cylinder head as a cast component or is a casting that incorporates or forms the exhaust ports. Advantageously, the cast core can be demolded upwards. However, this results in a less than ideal flow path, which can lead to material separation within the respective exhaust port, further reducing the effective flow cross-section.

[0004] Possible options to at least reduce or avoid the aforementioned disadvantages and problems include, for example, a cast surface with a tapered valve seat ring, which is cost-effective but results in very poor flow characteristics. Furthermore, the use of a 2D contour milling cutter would be conceivable. However, for manufacturing reasons, this can only be machined parallel to the cylinder axis. This results in only moderate advantages in flow guidance, mainly in that wall thicknesses can be reduced compared to a cast surface because casting tolerances are not required. This results in slightly larger channel cross-sections, but significant flow separation (flow angles) remains only marginally optimizable. However, this approach does result in significantly higher costs (longer tool life).Furthermore, 5-axis machining of the exhaust port in the area of ​​the valve seat ring would be conceivable, but this would lead to very high costs and therefore only seems practical for motorsport applications. However, this would allow for a particularly advantageous flow contour with favorable cross-sections and minimal flow separation, resulting in a maximum effective flow cross-sectional area.

[0005] The invention provides for a cylindrical recess in each exhaust port, and thus for each exhaust valve, on the side of the exhaust port facing the spark plug. This ensures a particularly cost-effective way to achieve a suitably large airflow cross-section in each exhaust port. The cylindrical recess is created by a mechanical process, for example, a one-dimensional movement of a tool or the cylinder head as the workpiece. In other words, the cylindrical recess can be produced by a single, one-dimensional movement, making its manufacture particularly time- and cost-efficient.The cylindrical indentation allows for a significantly larger flow cross-section in the respective exhaust channel, and compared to conventional solutions, flow angles in critical areas can be considerably optimized. It has been found that the invention can achieve 90 percent of the flow rate of a 5-axis machining operation, while the cylindrical indentation can be manufactured much more cost-effectively. This enables particularly efficient operation of the internal combustion engine in a very cost-effective manner.

[0006] Further advantages, features, and details of the invention will become apparent from the following description of a preferred embodiment and from the drawing. The features and combinations of features mentioned above in the description, as well as those mentioned below in the figure description and / or shown in the figures alone, can be used not only in the combinations specified, but also in other combinations or individually, without departing from the scope of the invention.

[0007] The drawing shows in: Fig. 1 is a partial schematic top view of an internal combustion engine, showing a combustion chamber roof; Fig. 2 is a partial schematic and cutaway perspective view of the internal combustion engine; Fig. 3 is a partial schematic and cutaway side view of the internal combustion engine along a [context missing] Fig. 1 section line AA shown; and Fig. 4 shows a schematic and sectioned rear view of the internal combustion engine along a section in Fig. 1 shown section line BB.

[0008] In the figures, identical or functionally equivalent elements are provided with the same reference symbols.

[0009] Fig. 1 Figure 1 shows a partial schematic top view of an internal combustion engine 10 designed as a reciprocating piston engine, i.e., a reciprocating piston machine, for a motor vehicle, in particular for a motor car and most preferably for a passenger car. The internal combustion engine 10 has at least one combustion chamber 12, which is partially enclosed by a cylinder 14 and partially by a combustion chamber roof 16 ( Fig. 2 The combustion chamber 14 is formed by a first housing element of the internal combustion engine 10, wherein the first housing element is, for example, a cylinder housing, in particular a cylinder crankcase. The combustion chamber roof 16 is formed by a second housing element of the internal combustion engine 10, designed as a cylinder head 18, wherein the cylinder head 18 is formed separately from the first housing element and connected to the first housing element. The combustion chamber 12 is also partially bounded by a piston, which is arranged to be translationally movable within the cylinder 14.

[0010] The combustion chamber 12 has, specifically, two exhaust ports 20, which are formed by the cylinder head 18, i.e., delimited, and thus run within the cylinder head 18. Each exhaust port 20 is assigned, specifically, a corresponding exhaust valve 22. Furthermore, the combustion chamber 12 has, specifically, two intake ports 24. The intake ports 24 are also formed by the cylinder head 18, i.e., delimited, so that the intake ports 24 run within the cylinder head 18. Each intake port 24 is assigned, specifically, a corresponding intake valve 26. Additionally, the combustion chamber 12 has, specifically, a spark plug 28, which is formed separately from the cylinder head 18 and is held by the cylinder head 18. For example, the cylinder head 18 has a spark plug well in which the spark plug 28 is at least partially located. This is evident from... Fig. 1 There is also a water jacket 30, which, for example, runs at least partially within the cylinder head 18 and is thus formed by the cylinder head 18. A liquid coolant, which contains at least water, can flow through the water jacket 30. The spark plug 28 can be cooled by means of the coolant flowing through the water jacket 28. It can be seen that the spark plug 28 is at least partially surrounded on its outer circumference by the water jacket 30, with at least a respective section of the water jacket 30 being located between the spark plug 28 and the respective exhaust port 20 or the respective exhaust valve 22. Fig. 1 It is evident that the spark plug 28 is located at least partially between the exhaust ports 20, in particular between the exhaust valves 22. Specifically, each exhaust port 20 has an inlet opening through which the exhaust port 20, considered on its own, opens into the combustion chamber 12. Thus, exhaust gas from the combustion chamber 12 can flow through the respective inlet opening and into the respective exhaust port 20, allowing the exhaust gas from the combustion chamber 12 to be discharged via the exhaust ports 20. The spark plug 28 is located at least partially between the inlet openings of the exhaust ports 20.

[0011] In order to achieve a particularly efficient operation of the internal combustion engine 10 in a particularly cost-effective manner, a respective cylindrical indentation 32 is provided in each exhaust port 20 and thus each exhaust valve 22 on a respective side S of the respective exhaust port 20 facing the spark plug 28.

[0012] Out of Fig. 2 The respective conical machining 34 of the respective exhaust port 20 is particularly clearly visible. Furthermore, it is particularly clear from Fig. 2 The cylindrical groove 32, designed as a one-dimensional groove, i.e., a 1D groove, is recognizable. This means, in particular, that the respective cylindrical groove 32 is produced by a one-dimensional relative movement between the cylinder head 18 and a tool by which the respective groove 32 is produced. For example, the respective tool is a milling cutter or milling head, so that, for example, the respective groove 32 is a mechanical machining operation of the cylinder head 18, specifically designed as a milling operation.

[0013] In Fig. 3 A first streamline is illustrated by 36. Streamline 36 illustrates a first flow of the exhaust gas passing through the respective inlet opening and thus entering and passing through the respective outlet channel 20, whereby the first flow of the exhaust gas illustrated by streamline 36 occurs, or would occur, if the respective outlet channel 20 did not have the respective indentation 32. Furthermore, illustrated in Fig. 3 A second streamline 38 represents a second flow of the exhaust gas passing through the respective inlet opening and thus entering and flowing through the respective outlet channel 20. This second flow is caused by the respective outlet channel 20 having the respective cylindrical indentation 32. Streamlines 36 and 38 show that the respective indentation 32 significantly improves the flow of the exhaust gas, resulting in particularly efficient and fuel-efficient operation of the internal combustion engine 10. Furthermore, the respective indentation 32 can be manufactured cost-effectively.

[0014] Furthermore, it is from Fig. 3 It is evident that each indentation 32 has a first central axis 40. Furthermore, the cylinder 14 has a second central axis, which is also referred to as the cylinder axis. For example, the cylinder 14 is at least substantially rotationally symmetrical with respect to its cylinder axis (second central axis). Fig. 3 The first angle is denoted by α, wherein the first central axis 40 encloses the first angle α with a line 42. The line 42 runs parallel to the cylinder axis and is spaced apart from it. The respective first central axis 40 runs in a first plane parallel to and spaced apart from the second central axis (cylinder axis), which runs parallel to a second plane extending centrally between the exhaust ports 20, particularly between the inlet openings, in which the second central axis (cylinder axis) runs. Viewed in this previously defined first plane, the respective first central axis 40 encloses the first angle α with the respective line 42, which runs parallel to the second central axis and in the first plane. This angle α is preferably in a range from 20 degrees inclusive to 60 degrees inclusive.

[0015] In Fig. 4 The tool 44, mentioned above, is illustrated by means of which the respective cylindrical groove 32 is produced. Thus, the respective tool 44 illustrates the respective cylindrical groove 32 itself. Furthermore, in Fig. 4 A second angle, designated β, is shown, which is enclosed, for example, by the respective tool 44, in particular by its third central axis, and the second central axis in a third plane in which both central axes 40 run. Thus, for example, the second angle β, viewed in the third plane, is enclosed by the respective first central axis 40 and the second central axis (cylinder axis), wherein preferably the second angle β lies in a range from 1 degree inclusive to 20 degrees inclusive. This causes the respective upper end E of the respective groove 32, facing away from the combustion chamber 12, to be inclined away from the spark plug 28.

[0016] Furthermore, in Fig. 4 the in Fig. 4 The spark plug well, designated 46, is recognizable, in which the spark plug 28 is at least partially arranged.

[0017] The tool 44, for example, has a first diameter, in particular a first inner diameter, wherein, for example, the first diameter is in a range from 5 mm inclusive to 16 mm inclusive. For example, the first diameter corresponds to a respective second diameter, in particular a respective first inner diameter, of the respective cylindrical groove 32. Thus, it is provided, for example, that the respective second diameter of the respective cylindrical groove 32 is in a range from 5 mm inclusive to 16 mm inclusive. Reference symbol list

[0018] 10 Internal combustion engine 12 Combustion chamber 14 Cylinder 16 Combustion chamber roof 18 Cylinder head 20 Exhaust port 22 Exhaust valve 24 Intake port 26 Intake valve 28 Spark plug 30 Water jacket 32 ​​Cylindrical recess 34 Taper machining 36 First streamline 38 Second streamline 40 First center axis 42 Straight line 44 Tool 46 Spark plug well End Side α First angle β Second angle

Claims

1. Internal combustion engine (10) for a motor vehicle, comprising at least one combustion chamber (12), and comprising at least one cylinder head (18), which combustion chamber has at least one combustion chamber roof (16) that partially limits the combustion chamber (12), to which combustion chamber roof two exhaust ports (20) of the cylinder head (18) and a spark plug (28) held on the cylinder head (18) are assigned, which spark plug is arranged at least partially between the exhaust ports (20), characterized in that each exhaust port (20) has a cylindrical recess (32) in the corresponding exhaust port (20) on a corresponding side (S) of the corresponding exhaust port (20), which side faces the spark plug (28).

2. Internal combustion engine (10) according to claim 1, characterized in that the corresponding cylindrical recess (32) has a corresponding first central axis (40), the combustion chamber (12) being partially limited by a cylinder (14) of the internal combustion engine (10), which cylinder (14) has a second central axis.

3. Internal combustion engine (10) according to claim 2, characterized in that the corresponding first central axis (40) runs in a corresponding first plane that is parallel to the second central axis and spaced apart from the second central axis, and, in the corresponding first plane, which runs parallel to a second plane that extends centrally between the exhaust ports (20) and in which the second central axis runs, encloses a first angle (α) together with a straight line (42) that runs parallel to the second central axis and in the first plane, which angle lies in a range from 20 degrees inclusive to 60 degrees inclusive.

4. Internal combustion engine (10) according to claim 2 or 3, characterized in that the corresponding first central axis (40), viewed in a third plane in which both first central axes (40) run, encloses a second angle (β) together with the second central axis, which second angle lies in a range from 1 degree inclusive to 20 degrees inclusive, whereby a corresponding end (E) of the corresponding recess (32), which end faces away from the combustion chamber (12), is inclined away from the spark plug (28).

5. Internal combustion engine (10) according to any of the preceding claims, characterized in that the corresponding recess (32) has a corresponding diameter which lies in a range from 5 millimeters inclusive to 16 millimeters inclusive.