Piston and internal combustion engine

Abstract

The invention relates to a piston (8A, 8B) for a hydrogen-operated internal combustion engine (7), comprising a piston head (11), a piston skirt (10) connected to the piston head (11), and a combustion bowl (24) provided on the piston head (11), wherein the piston (8A, 8B) has a piston diameter (32) which can be measured on the piston skirt (10), wherein the combustion bowl (24) has a minimum combustion bowl volume (29), the magnitude of which is 2.9674 times the magnitude of the piston diameter (32) minus 220.68, and wherein the combustion bowl (24) has maximum combustion bowl volume (29), the magnitude of which is 4.1893 times the magnitude of the piston diameter (32) minus 311.55.

Description

[0001] KS Kolbenschmidt GmbH 1

[0002] PISTONS AND COMBUSTION ENGINE

[0003] The present invention relates to a piston for a hydrogen-powered internal combustion engine and a hydrogen-powered internal combustion engine having such a piston.

[0004] To prevent the emission of carbon dioxide and hydrocarbons from internal combustion engines, there are approaches to operating them with gaseous hydrogen. In this case, the internal combustion engine burns a hydrogen / air mixture. However, according to internal company findings, the problem that this can arise is that, due to the high flammability of hydrogen / air mixtures, undesirable knocking combustion can occur. This results from the hydrogen / air mixture igniting at local hot spots, for example, at the sharp edges of a piston crown of an internal combustion engine piston. This knocking combustion can have a negative impact on the service life of the internal combustion engine or of components of the internal combustion engine, such as the aforementioned piston. This must be improved.

[0005] Against this background, one object of the present invention is to provide an improved piston for a hydrogen-powered internal combustion engine.

[0006] Accordingly, a piston for a hydrogen-powered internal combustion engine is proposed. The piston comprises a piston head, a piston skirt connected to the piston head, and a combustion chamber recess provided on the piston head. The piston has a piston diameter measurable at the piston skirt. The combustion chamber recess has a minimum combustion chamber volume whose magnitude is 2.9674 times the piston diameter minus 220.68, and the combustion chamber recess has a maximum combustion chamber volume whose magnitude is 4.1893 times the piston diameter minus 311.55.

[0007] By selecting the combustion chamber bowl volume between the aforementioned minimum and maximum values, it has surprisingly been shown that knocking combustion can be prevented. This significantly increases the service life of a hydrogen-powered combustion engine with such a piston, or rather the service life of the piston itself. Furthermore, it results in an increase in the efficiency of hydrogen combustion.

[0008] The hydrogen-powered internal combustion engine can be a gasoline engine. The hydrogen-powered internal combustion engine can comprise an engine block and a plurality of pistons accommodated in piston bores of the engine block. The piston can be referred to, in particular, as a hydrogen-powered piston or a hydrogen piston. This means, in particular, that the terms "piston" and "hydrogen piston" can be used interchangeably in this context.

[0009] In particular, the piston can be assigned a symmetry or central axis, to which the piston can be constructed substantially rotationally symmetrically. This aforementioned central axis can be formed, in particular, by a central axis of a cylinder that surrounds surfaces of the piston skirt and has a minimal diameter, wherein the central axis of this cylinder is arranged perpendicular to a piston pin bore, in particular to a central axis of the piston pin bore.

[0010] The piston can also be assigned a coordinate system with a width direction (or x-direction), a height direction (or y-direction), and a depth direction (or z-direction). The y-direction can also be referred to as the axial direction. The terms "y-direction" and "axial direction" are therefore interchangeable. The directions are oriented perpendicular to each other. The central axis coincides with the y-direction or is oriented parallel to the y-direction. The piston is also assigned a radial direction. The radial direction is oriented perpendicular to the central axis and points away from it.

[0011] The piston head and piston skirt can be two separate components that are joined to form the piston. For example, the piston head and piston skirt can be joined together by a material bond. Material bonded connections are non-detachable connections that can only be separated by destroying the connecting elements and / or the connecting parts. A material bond can be achieved, for example, by welding. For example, the piston head and piston skirt are welded together.

[0012] The piston is preferably made of a metallic material. For example, the piston can be made of a light metal alloy, in particular an aluminum alloy. However, the piston can also be made of a steel alloy. Furthermore, the piston can also be made of cast iron.

[0013] The fact that the combustion chamber bowl is "provided" on the piston head means, in particular, that the combustion chamber bowl is machined into the piston head or arranged on the piston head. In particular, the combustion chamber bowl is a depression machined into the piston head. The piston preferably has a piston crown that encompasses the combustion chamber bowl. The combustion chamber bowl is recessed relative to a piston crown section of the piston crown that extends annularly around the central axis. This means, in particular, that the combustion chamber bowl is recessed or recessed relative to the piston crown section, viewed along the central axis or along the y-direction. The combustion chamber bowl is open away from the piston skirt. The combustion chamber bowl can be delimited, away from the piston skirt, in particular by a plane in which the piston crown section lies. This plane is oriented perpendicular to the central axis.

[0014] In this context, the term "magnitude" can be understood as the numerical value of any quantity, especially independent of any unit of that quantity. The quantity can be a length or diameter, as well as an area or volume.

[0015] The piston diameter is specifically defined as the diameter of the smallest possible cylinder that encloses a piston skirt, i.e., the skirt sections of the piston. This cylinder is oriented perpendicular to the center axis of the piston pin bore. In particular, a first skirt section and a second skirt section are provided. The skirt sections together form the so-called piston skirt of the piston. The skirt sections can be connected to one another by means of wall sections. The piston diameter is preferably specified in millimeters (mm).

[0016] The combustion chamber bowl volume is defined as the volume enclosed or contained by the combustion chamber bowl surface and the aforementioned plane. The combustion chamber bowl volume can be determined or calculated, for example, using a CAD (Computer Aided Design) model of the combustion chamber bowl or piston. In the simplest case, to determine the combustion chamber bowl volume, the combustion chamber bowl can be filled with water up to the aforementioned plane or up to the piston crown section, and the water absorbed in the combustion chamber bowl can be poured into a measuring cup to determine the combustion chamber bowl volume based on the volume of water read from the measuring cup.

[0017] The combustion chamber bowl has a minimum combustion chamber volume of 2.9674 times the piston diameter less 220.68. At the same time, the combustion chamber bowl has a maximum combustion chamber volume of 4.1893 times the piston diameter less 311.55. The combustion chamber volume is measured in cubic millimeters (mm 3 ) is indicated.

[0018] According to one embodiment, the combustion chamber bowl has a combustion chamber volume which is limited by a minimum combustion chamber volume and a maximum combustion chamber volume, the amounts of which are each dependent on the piston diameter, where - minimum combustion chamber volume = 2.9674 mm 2 * Piston diameter - 220.68 mm 3 , and maximum combustion chamber volume = 4.1893 mm 2 * Piston diameter - 311.55 mm 3 .

[0019] Here, the value of the piston diameter in mm and the values ​​of the minimum combustion chamber volume and the maximum combustion chamber volume in mm 3 specified.

[0020] According to a further embodiment, a piston for a hydrogen-powered internal combustion engine is proposed. The piston comprises a piston head, a piston skirt connected to the piston head, and a combustion chamber bowl provided on the piston head. The piston has a piston diameter measurable at the piston skirt. The combustion chamber bowl has a combustion chamber volume limited by a minimum combustion chamber volume and a maximum combustion chamber volume, the amounts of which are each dependent on the piston diameter, where: minimum combustion chamber volume = 2.9674 mm 2 * Piston diameter ■ 220.68 mm 3 , and maximum combustion chamber volume = 4.1893 mm 2 * Piston diameter - 311.55 mm3 .

[0021] According to a further embodiment, a piston for a hydrogen-powered internal combustion engine is proposed. The piston comprises a piston head, a piston skirt connected to the piston head, and a combustion chamber bowl provided on the piston head. The piston has a piston diameter measurable at the piston skirt. The combustion chamber bowl has a minimum combustion chamber volume of 2.9674 times the piston diameter minus 220.68, and the combustion chamber bowl has a maximum combustion chamber volume of 4.1893 times the piston diameter minus 311.55.

[0022] According to a further embodiment, the piston head has at least one valve pocket with a valve pocket volume, wherein the valve pocket volume is both part of the minimum combustion chamber volume and part of the maximum combustion chamber volume.

[0023] Multiple valve pockets can be provided. Valve tappets engage the valve pockets during operation of the internal combustion engine. The valve pockets can be evenly distributed around the center axis, but this is not mandatory. The number of valve pockets preferably corresponds to the number of valves per piston. For example, four valve pockets are provided on the piston. Each valve pocket has, in particular, a valve pocket volume, wherein the valve pocket volumes of all valve pockets are part of both the minimum combustion chamber bowl volume and the maximum combustion chamber bowl volume. Accordingly, the combustion chamber bowl has a minimum combustion chamber bowl volume that is 2.9674 times the piston diameter less a value of 220.68. However, the valve pocket volumes of the valve pockets are part of the minimum combustion chamber bowl volume.At the same time, the combustion chamber bowl has a maximum combustion chamber volume of 4.1893 times the piston diameter less a value of 311.55. However, the valve pocket volumes are part of the maximum combustion chamber volume. In this case, the combustion chamber volume is also measured in cubic millimeters (mm). 3 ) is indicated.

[0024] According to a further embodiment, the at least one valve pocket is provided on a top land of the piston head.

[0025] The top land preferably runs around the combustion chamber bowl. The combustion chamber bowl can be arranged partially within the top land. In particular, the piston has an annular field. The annular field forms in particular a substantially cylindrical outer surface of the piston head, which can be constructed rotationally symmetrically to the central axis. The annular field can have a plurality of annular grooves arranged one above the other as viewed along the y-direction. The annular grooves are suitable for receiving piston rings. For example, two or three such annular grooves are provided. The top land adjoins the piston crown and is part of the annular field. However, the top land does not have an annular groove for receiving a piston ring as mentioned above. As viewed along the y-direction, the top land ends at the piston crown section or at the plane that closes off the combustion chamber bowl at the top.

[0026] According to a further embodiment, the at least one valve pocket breaks through the top land as viewed along a radial direction of the piston.

[0027] Thus, the valve pocket interrupts the top land, or the valve pockets interrupt the top land. Viewed radially, the combustion chamber bowl is thus open to the area surrounding the piston through the valve pocket or the valve pockets.

[0028] According to a further embodiment, the at least one valve pocket is ring-segment-shaped.

[0029] A "ring segment" is understood here to mean a section of a ring. Preferably, as mentioned above, several valve pockets are provided, which can be arranged at a distance from one another along a circumferential direction of the top land.

[0030] According to a further embodiment, the piston has a ratio of a compression height of the piston to the piston diameter of 0.4 to 0.65.

[0031] The compression height is defined as the distance between the center axis of the piston pin bore and an upper edge of the piston, namely the plane enclosing the combustion chamber bowl, or the piston crown section. The ratio of the compression height to the piston diameter is in particular 0.2 to 0.85, preferably 0.3 to 0.75, more preferably 0.4 to 0.65. The compression height is preferably specified in millimeters (mm).

[0032] According to a further embodiment, the piston head has a cooling channel that runs completely around a central axis of the piston.

[0033] The cooling channel is preferably constructed rotationally symmetrically to the central axis. The cooling channel can in particular be toroidal. A cooling oil, in particular engine oil, can be conducted through the cooling channel in order to dissipate heat introduced into the piston during operation. For this purpose, the cooling oil can be injected into the cooling channel using an injection nozzle arranged below the piston. The cooling channel can be introduced into the piston, for example, using a rinseable salt core during manufacture. Alternatively, the cooling channel can also be introduced into the piston when subcomponents are joined together. With the help of a plurality of bores, the cooling channel can be in fluid communication with an interior of the piston. Preferably, a plurality of bores are provided. For example, during operation of the piston, cooling oil can be injected into the interior using the aforementioned injection nozzle.At least a portion of the cooling oil flows through the holes into the cooling channel and out again. The cooling oil then dissipates heat from the piston.

[0034] According to a further embodiment, the combustion chamber bowl extends along the central axis into the piston head at least up to the level of the cooling channel.

[0035] This means, in particular, that the cooling channel and the combustion chamber bowl can be arranged at least partially at the same height when viewed along the y-direction. In other words, the combustion chamber bowl covers the cooling channel at least partially when viewed along the radial direction.

[0036] According to a further embodiment, the combustion chamber bowl has an edge-free combustion chamber bowl surface.

[0037] The combustion chamber bowl surface is preferably constructed rotationally symmetrically to the central axis. The combustion chamber bowl surface can have a substantially W-shaped geometry in cross-section. The W-shaped geometry can have a central section, a first wall section extending diagonally downwards from the central section counter to the y-direction, and a second wall section adjoining the first wall section and extending diagonally upwards along the y-direction. The second wall section ends at the plane closing the combustion chamber bowl. In particular, the combustion chamber bowl surface continuously widens starting from the central section when viewed along the y-direction. This means, in particular, that a diameter of the combustion chamber bowl becomes increasingly larger starting from the central section along the y-direction towards the plane.Thus, no cross-sectional constrictions, undercuts, steps, or the like are provided on the combustion chamber bowl surface. The combustion chamber bowl is thus edge-free or edgeless. "Edge-free" or "edgeless" can mean, in particular, that the combustion chamber bowl surface has no edges. In particular, the central section and the wall sections of the combustion chamber bowl surface merge into one another with rounded portions. In particular, the rounded portions have a radius of greater than 1 mm, preferably greater than 2 mm, more preferably greater than 3 mm, more preferably greater than 4 mm, more preferably greater than 5 mm. The edge-free combustion chamber bowl surface prevents sharp edges in the combustion chamber bowl area. Sharp edges could otherwise create local hot spots where the hydrogen / air mixture could ignite uncontrollably. However, this is reliably prevented by the edge-free combustion chamber bowl surface.

[0038] Furthermore, a hydrogen-powered internal combustion engine with at least one such piston is proposed.

[0039] The hydrogen-powered internal combustion engine can be a gasoline engine. The hydrogen-powered internal combustion engine can comprise an engine block and several pistons accommodated in piston bores of the engine block. For example, the hydrogen-powered internal combustion engine can have three, four, five, six, or more than six pistons. The hydrogen-powered internal combustion engine can also be referred to as a hydrogen internal combustion engine. The terms "hydrogen-powered internal combustion engine" and "hydrogen internal combustion engine" can therefore be interchanged. "Hydrogen-powered" in this context means that the hydrogen-powered internal combustion engine burns gaseous hydrogen with the addition of atmospheric oxygen. The combustion of the hydrogen converts chemical energy into mechanical work in the hydrogen-powered internal combustion engine.

[0040] The embodiments and features described for the proposed piston apply accordingly to the proposed hydrogen-powered internal combustion engine and vice versa.

[0041] "One" in this case is not necessarily limited to a single element. Rather, multiple elements, such as two, three, or more, may be included. Any other counting term used here should not be understood as implying a limitation to the exact number of elements mentioned. Rather, numerical deviations upwards and downwards are possible, unless otherwise stated.

[0042] Further possible implementations of the piston and / or the hydrogen-powered internal combustion engine also include combinations of features or embodiments described above or below with respect to the exemplary embodiments that are not explicitly mentioned. In this case, the person skilled in the art will also add individual aspects as improvements or additions to the respective basic form of the piston and / or the hydrogen-powered internal combustion engine.

[0043] Further advantageous configurations and aspects of the piston and / or the hydrogen-powered internal combustion engine are the subject of the dependent claims and the exemplary embodiments of the piston and / or the hydrogen-powered internal combustion engine described below. The piston and / or the hydrogen-powered internal combustion engine are explained in more detail below using preferred embodiments with reference to the accompanying figures.

[0044] Fig. 1 shows a schematic side view of an embodiment of a vehicle!

[0045] Fig. 2 shows a schematic perspective view of an embodiment of a piston for an internal combustion engine of the vehicle according to Fig. 1;

[0046] Fig. 3 shows a schematic sectional view of the piston according to Fig. 2;

[0047] Fig. 4 shows a further schematic sectional view of the piston according to Fig. 2;

[0048] Fig. 5 shows a schematic perspective view of another embodiment of a piston for an internal combustion engine of the vehicle according to Fig. 1;

[0049] Fig. 6 shows a schematic sectional view of the piston according to Fig. 5; and

[0050] Fig. 7 shows a further schematic sectional view of the piston according to Fig. 5.

[0051] In the figures, identical or functionally equivalent elements have been given the same reference numerals unless otherwise stated.

[0052] Fig. 1 shows a schematic side view of an embodiment of a vehicle 1. The vehicle 1 is a motor vehicle, in particular a passenger car. The vehicle 1 can also be a commercial vehicle, for example a truck, a harvester, or a construction machine. Furthermore, the vehicle 1 can also be a military vehicle. Furthermore, the vehicle can also be an aircraft, a watercraft, or a rail vehicle. However, it is assumed below that the vehicle 1 is a motor vehicle, in particular a passenger car.

[0053] The vehicle 1 comprises a body 2, which encloses a passenger compartment or vehicle interior 3 of the vehicle 1. A driver and passengers can be located in the vehicle interior 3. The body 2 separates an environment 4 of the vehicle 1 from the vehicle interior 3. The vehicle interior 3 is accessible from the environment 4 by means of doors.

[0054] Vehicle 1 comprises a chassis with several wheels 5, 6. The number of wheels 5, 6 is fundamentally arbitrary. Preferably, vehicle 1 has four wheels 5, 6. However, vehicle 1 may, for example, have six wheels 5, 6. Wheels 5, 6 are part of a chassis of vehicle 1. Only two wheels 5, 6 may be driven. However, all wheels 5, 6 may also be driven. In this case, vehicle 1 is an all-wheel drive vehicle.

[0055] The vehicle 1 comprises an internal combustion engine or an internal combustion engine 7. The internal combustion engine 7 can be a gasoline engine. The vehicle 1 can be powered solely by the internal combustion engine 7. However, the vehicle 1 can also be a hybrid vehicle. In this case, the vehicle 1 has at least one electric motor in addition to the internal combustion engine 7. The internal combustion engine 7 comprises an engine block and a plurality of pistons accommodated in piston bores of the engine block. For example, the internal combustion engine 7 can have three, four, five, six, or more than six pistons.

[0056] The internal combustion engine 7 in this case is a hydrogen-powered internal combustion engine and can therefore also be referred to as such. The terms "internal combustion engine" and "hydrogen-powered internal combustion engine" can therefore be interchanged. "Hydrogen-powered" in this case means that the internal combustion engine 7 burns gaseous hydrogen with the addition of atmospheric oxygen. The combustion of the hydrogen converts chemical energy into mechanical work of the internal combustion engine 7.

[0057] Fig. 2 shows a schematic perspective view of an embodiment of a piston 8A for the internal combustion engine 7. Fig. 3 shows a schematic sectional view of the piston 8A. Fig. 4 shows a further schematic sectional view of the piston 8A. Reference is made below to Figs. 2 to 4 simultaneously.

[0058] The piston 8A can be part of a vehicle 1 as previously explained, in particular the internal combustion engine 7. However, the piston 8A is particularly preferably part of a commercial vehicle. In this case, the vehicle 1 is a commercial vehicle. The internal combustion engine 7 and thus the piston 8A can be used in any vehicle 1, ship, machine, or the like. Furthermore, the internal combustion engine 7 or the piston 8A can also be used for stationary applications, such as for generators, power, heat, or the like.

[0059] The piston 8A is made of a metallic material. For example, the piston 8A can be made of a light metal alloy, in particular an aluminum alloy. However, the piston 8A can also be made of a steel alloy. Furthermore, the piston 8A can also be made of cast iron. The piston 8A can be composed of several subcomponents that are integrally connected to one another. In integrally bonded connections, the connecting partners are held together by atomic or molecular forces. Integral connections are non-detachable connections that can only be separated from one another by destroying the connecting means and / or the connecting partners. Integral connections can be achieved, for example, by gluing, soldering, or welding. For example, the previously mentioned subcomponents of the piston 8A are welded to one another, in particular friction welded.

[0060] The piston 8A can comprise a symmetry or central axis 9, to which the piston 8A can be constructed essentially rotationally symmetrically. A coordinate system with a width direction or x-direction x, a height direction or y-direction y, and a depth direction or z-direction z is assigned to the piston 8A. The y-direction y can also be referred to as the axial direction. The terms "y-direction" and "axial direction" are therefore interchangeable. The directions x, y, and z are oriented perpendicular to one another. The central axis 9, in particular, coincides with the y-direction y or is oriented parallel to it. Furthermore, a radial direction R is assigned to the piston 8A. The radial direction R is oriented perpendicular to the central axis 9 and points away from it.

[0061] The piston 8A has a piston base or piston skirt 10 and a piston head 11. Viewed along the central axis 9, the piston skirt 10 is arranged below the piston head 11. The piston skirt 10 has a piston hub with a pin bore 12, in which a pin (not shown) for coupling the piston 8A to a connecting rod (not shown) of the internal combustion engine 7 can be received. A symmetry or central axis 13 of the pin bore 12 intersects the central axis 9 or is offset from it. Furthermore, the central axis 13 is oriented perpendicular to the central axis 9. The central axis 13 coincides with the z-direction z or is oriented parallel to it.

[0062] In the orientation of Fig. 3 on both sides of the bolt hole 12 there is a

[0063] Shaft sections 14, 15 are provided. A first shaft section 14 and a second shaft section 15 are provided. The shaft sections 14, 15 can be cylindrical in section. In other words, the shaft sections 14, 15 can form part of a cylinder that is rotationally symmetrical to the central axis 9. The shaft sections 14, 15 together form a so-called piston skirt of the piston 8A. The shaft sections 14, 15 can be rotationally symmetrical to the central axis 9 in section. In this case, however, the shaft sections 14, 15 in particular do not form a complete cylinder. One of the shaft sections 14, 15 forms a pressure side of the piston 8A, while the other of the shaft sections 14, 15 forms a counter-pressure side of the piston 8A.

[0064] The skirt sections 14, 15 are connected to one another by means of wall sections 16, 17. A first wall section 16 and a second wall section 17 are provided. The radial direction R points away from the central axis 9 in the outward direction of the skirt sections 14, 15. The pin bore 12 penetrates the wall sections 16, 17. The skirt sections 14, 15 and the wall sections 16, 17 enclose an interior space 18 of the piston skirt 10. The interior space 18 is open downwards in the orientation of Figs. 2 to 4. The aforementioned pin for coupling the piston 8A to the connecting rod runs along the central axis 13 through the interior space 18.

[0065] The piston 8A has a cooling channel 19 which runs completely around the central axis 9 and is preferably constructed rotationally symmetrically thereto. The cooling channel 19 is in particular toroidal. A cooling oil, in particular engine oil, can be conducted through the cooling channel 19 in order to dissipate heat Q introduced into the piston 8A during operation. For this purpose, the cooling oil can be injected into the cooling channel 19 by means of an injection nozzle arranged below the piston 8A in the orientation of Figs. 2 to 4. The cooling channel 19 can be introduced into the piston 8A, for example, using a rinseable salt core during its manufacture. Alternatively, the cooling channel 19 can also be formed when the aforementioned sub-components of the

[0066] Piston 8A is inserted into it.

[0067] With the help of several bores (not shown), the cooling channel 19 can be in fluid communication with the interior 18. The number of bores is fundamentally arbitrary. Preferably, several bores are provided, which can be arranged evenly distributed around the central axis 9. The bores can also be arranged unevenly distributed around the central axis 9. For example, during operation of the piston 8A in the orientation of Fig. 2 to 4, cooling oil can be injected from below into the interior 18 with the help of the aforementioned injection nozzle. At least a portion of the cooling oil passes through the bores into the cooling channel 19 and out again from there. Heat Q is then dissipated from the piston 8A with the cooling oil.

[0068] The piston head 11 has a piston crown 20, which faces a cylinder head of the internal combustion engine 7. A large portion of the heat Q is also introduced into the piston crown 20. The piston crown 20 faces, in particular, a combustion chamber 21 of the internal combustion engine 7. The piston crown 20 comprises an annular piston crown section 22, which defines a plane 23 oriented perpendicular to the central axis 9.

[0069] Furthermore, the piston crown 20 has a combustion chamber bowl 24 which is set back with respect to the piston crown section 22. Viewed along the central axis 9 or along the y-direction y, the combustion chamber bowl 24 is thus offset or recessed with respect to the piston crown section 22. In the orientation of Figs. 3 and 4, the combustion chamber bowl 24 is bounded at the top by the plane 23. Viewed along the central axis 9, the combustion chamber bowl 24 extends at least to the level of the cooling channel 19. The combustion chamber bowl 24 has a combustion chamber bowl surface 25 which can have any desired geometry. The combustion chamber bowl surface 25 is rotationally symmetrical to the central axis 9.In cross-section, the combustion chamber bowl surface 25 has a substantially W-shaped geometry with a central section 26, a first wall section 27 extending obliquely downwards from the central section 26 counter to the y-direction y, and a second wall section 28 adjoining the first wall section 27 and extending obliquely upwards along the y-direction y. The second wall section 28 ends at plane 23.

[0070] The combustion chamber bowl surface 25 continuously widens from the central section 26 along the y-direction y. This means, in particular, that the diameter of the combustion chamber bowl 24 becomes increasingly larger from the central section 26 along the y-direction y toward the plane 23. Thus, no cross-sectional constrictions, undercuts, steps, or the like are provided on the combustion chamber bowl surface 25. The combustion chamber bowl surface 25 is thus edge-free or edgeless. In particular, the central section 26 and the wall sections 27, 28 merge into one another with rounded edges.

[0071] The combustion chamber bowl 24 is open at the top in the orientation shown in Figs. 2 to 4. The combustion chamber bowl 24 has a combustion chamber bowl volume 29. The combustion chamber bowl volume 29 is defined as a volume enclosed or enclosed by the combustion chamber bowl surface 25 and the plane 23. The combustion chamber bowl volume 29 can be determined or calculated, for example, using a CAD (Computer Aided Design) model of the combustion chamber bowl 24.

[0072] In the simplest case, to determine the combustion chamber bowl volume 29, the combustion chamber bowl 24 can be filled with water up to the level 23 or up to the piston crown section 22 and the water absorbed in the combustion chamber bowl 24 can be poured into a measuring cup in order to determine the combustion chamber bowl volume 29 based on the volume of water read from the measuring cup.

[0073] A wall 30 separates the combustion chamber bowl 24 from the interior 18. The wall 30 forms part of the combustion chamber bowl surface 25 on the front side. On the rear side, i.e., facing the interior 18, the wall 30 forms a so-called inner shape 31 of the piston 8A. The inner shape 31 can be conical or tapered.

[0074] The piston 8A has a piston diameter of 32. The piston diameter 32 is defined as the diameter of the smallest possible cylinder that includes the piston skirt, i.e., the skirt sections 14, 15. This cylinder is oriented perpendicular to the center axis 13. The combustion chamber bowl 24 preferably has a minimum combustion chamber volume 29, which is 2.9674 times the piston diameter 32 less a value of 220.68. At the same time, the combustion chamber bowl 24 has a maximum combustion chamber volume 29, which is 4.1893 times the piston diameter 32 less a value of 311.55. The combustion chamber volume 29 is measured in cubic millimeters (mm 3 ) is indicated.

[0075] Furthermore, the piston 8A has a compression height 33. The compression height 33 is defined as a distance between the central axis 13 and an upper edge of the piston 8A, namely the plane 23 or the piston crown section 22. A ratio of the compression height 33 to the piston diameter 32 is in particular 0.2 to 0.85, preferably 0.3 to 0.75, more preferably 0.4 to 0.65. A ring section or annular field 34 is provided on the piston head 11. The annular field 34 forms in particular a substantially cylindrical outer surface of the piston head 11, which can be constructed rotationally symmetrically to the central axis 9. The annular field 34 has a plurality of annular grooves 35 arranged one above the other as viewed along the y-direction y, only one of which is provided with a reference symbol in Fig. 4. The annular grooves 35 are suitable for receiving piston rings. For example, two or three such annular grooves 35 are provided.

[0076] Furthermore, the ring field 34 can also have a ring carrier 36. The ring carrier 36 runs completely around the central axis 9. In cross-section, the ring carrier 36 can be U-shaped. The ring carrier 36 can accommodate or carry a piston ring as mentioned above. The ring carrier 36 can be made of a different material than the piston head 11 or the piston 8A. For example, the ring carrier 36 can be made of a steel alloy, whereas the piston 8A can be made of an aluminum alloy. In this case, the ring carrier 36 can be an insert to which the piston 8A is cast using a casting process.

[0077] A top land 37 adjoining the piston crown section 22 is part of the ring zone 34. However, the top land 37 does not have the previously mentioned annular groove 35 for receiving a piston ring. Viewed along the y-direction y, the top land 37 ends at the piston crown section 22 or at the plane 23.

[0078] Fig. 5 shows a schematic perspective view of a further embodiment of a piston 8B for the internal combustion engine 7. Fig. 6 shows a schematic sectional view of the piston 8B. Fig. 7 shows a further schematic sectional view of the piston 8B. Reference is made below to Figs. 5 to 7 simultaneously. The structure of the piston 8B is essentially the same as that of the piston 8A. Therefore, only differences between the piston 8B and the piston 8A will be discussed below. All statements relating to the piston 8A are applicable to the piston 8B and vice versa.

[0079] In contrast to piston 8A, piston 8B has a plurality of valve pockets 38, of which only one is provided with a reference symbol in Figs. 5 to 7. Valve tappets engage in the valve pockets 38 during operation of the internal combustion engine 7. The valve pockets 38 can be arranged evenly distributed around the central axis 9. However, this is not absolutely necessary. The number of valve pockets 38 preferably corresponds to the number of valves per piston 8B. For example, four valve pockets 38 are provided.

[0080] The valve pockets 38 are preferably provided on the top land 37. The valve pockets 38 penetrate the top land 37 as viewed along the radial direction R of the piston 8B. The valve pockets 38 are preferably ring-segment-shaped.

[0081] Each valve pocket 38 has a valve pocket volume, wherein the valve pocket volumes of the valve pockets 38 are part of both the minimum combustion chamber bowl volume 29 and the maximum combustion chamber bowl volume 29. Accordingly, for piston 8B, the combustion chamber bowl 24 has a minimum combustion chamber bowl volume 29, which is 2.9674 times the piston diameter 32 less a value of 220.68. However, the valve pocket volumes of the valve pockets 38 are part of the minimum combustion chamber bowl volume 29.

[0082] At the same time, it also applies to piston 8B that the combustion chamber bowl 24 has a maximum combustion chamber volume 29, which is 4.1893 times the piston diameter 32 less a value of 311.55. However, the valve pocket volumes of the valve pockets 38 are part of the maximum combustion chamber volume 29. The combustion chamber volume 29 is measured in cubic millimeters (mm 3 ) is indicated.

[0083] A common valve pocket volume of all valve pockets 38 can be defined here as a volume difference between a piston blank whose structure, except for the valve pockets 38, is identical to that of the piston 8B, which does not yet have valve pockets 38, and the piston 8B itself, which already has the valve pockets 38. The valve pockets 38 can be milled into the piston blank or molded onto a casting mold that can be used to manufacture the piston blank.

[0084] Although the present invention has been described using exemplary embodiments, it can be modified in many ways.

[0085] LIST OF REFERENCE SYMBOLS

[0086] vehicle

[0087] body

[0088] Vehicle interior

[0089] Vicinity

[0090] wheel

[0091] wheel

[0092] Internal combustion engine A Piston B Piston

[0093] Center axis 0 Piston skirt 1 Piston head 2 Pin bore 3 Center axis 4 Skirt section 5 Skirt section 6 Wall section 7 Wall section 8 Interior 9 Cooling channel 0 Piston crown 1 Combustion chamber 2 Piston crown section 3 Plane 4 Combustion chamber bowl 5 Combustion chamber bowl surface 6 Center section 7 Wall section 28 Wall section

[0094] 29 combustion chamber bowl volume

[0095] 30 wall

[0096] 31 inner shape 32 piston diameter

[0097] 33 compression height

[0098] 34 Ringfeld

[0099] 35 ring groove

[0100] 36 Ring carrier 37 Flange

[0101] 38 valve pocket

[0102] Q Heat

[0103] R Radial direction x x-direction y y-direction z z-direction

Claims

PATENT CLAIMS 1. Piston (8A, 8B) for a hydrogen-powered internal combustion engine (7), with a piston head (11), a piston skirt (10) which is connected to the piston head (11), and a combustion chamber recess (24) provided on the piston head (11), wherein the piston (8A, 8B) has a piston diameter (32) which can be measured on the piston skirt (10), wherein the combustion chamber recess (24) has a minimum combustion chamber recess volume (29) whose amount is 2.9674 times the amount of the piston diameter (32) - 220.68, and wherein the combustion chamber recess (24) has a maximum combustion chamber recess volume (29) whose amount is 4.1893 times the amount of the piston diameter (32) - 311.

55.

2. Piston according to claim 1, characterized in that the piston head (11) has at least one valve pocket (38) with a valve pocket volume, wherein the valve pocket volume is both part of the minimum combustion chamber bowl volume (29) and part of the maximum combustion chamber bowl volume (29).

3. Piston according to claim 2, characterized in that the at least one valve pocket (38) is provided on a top land (37) of the piston head (11).

4. Piston according to claim 3, characterized in that that the at least one valve pocket (38) breaks through the top land (37) viewed along a radial direction (R) of the piston (8A, 8B).

5. Piston according to claim 3 or 4, characterized in that the at least one valve pocket (38) is ring-segment-shaped.

6. Piston according to one of claims 1 - 5, characterized in that the piston (8A, 8B) has a ratio of a compression height (33) of the piston (8A, 8B) TO the piston diameter (32) of 0.4 to 0.

65.

7. Piston according to one of claims 1 - 6, characterized in that the piston head (11) has a cooling channel (19) which runs completely around a central axis (9) of the piston (8A, 8B).

8. Piston according to claim 7, characterized in that the combustion chamber bowl (24) extends into the piston head (11) at least up to the level of the cooling channel (19) when viewed along the central axis (9).

9. Piston according to one of claims 1 - 8, characterized in that the combustion chamber bowl (24) has an edge-free combustion chamber bowl surface (25).

10. Hydrogen-powered internal combustion engine (7) with at least one piston (8A, 8B) according to one of claims 1 - 9.

Images