Internal combustion engine including a variable compression ratio device

Abstract

To enable a continuous reliable operation of a VCR system.SOLUTION: A piston 6 of an internal combustion engine is connected to a crosshead via a piston rod, and a crosshead is connected to a crankshaft via a connecting rod. A variable compression ratio device is provided with a fluid chamber arranged inside a crosshead pin 11 connected to the piston rod. In the fluid chamber, the piston rod is moveable relative to a bottom of the fluid chamber, and comprises cooling channels. The crosshead pin comprises a first flow path 15 for guiding a cooling fluid to be supplied to the cooling channels, and a second flow path 16 for guiding a cooling fluid to be discharged from the cooling channels. The first flow path is arranged at a first distance to a bottom plane of the fluid chamber, and the second flow path is arranged at a second distance to the bottom plane. The first distance is smaller than the second distance. The first flow path comprises a plurality of first channels uniformly arranged in a first cross-section of the crosshead pin parallel to the bottom plane.SELECTED DRAWING: Figure 3

Description

[Technical Field]

[0001] The present invention relates to an internal combustion engine, a method for operating an internal combustion engine, and a crosshead pin.

[0002] The present invention relates to an internal combustion engine, such as a large marine or ship engine or a stationary engine, preferably having a cylinder with a bore of at least 200 mm. The engine is preferably a two-stroke engine or a two-stroke cross-head engine. The engine may be a gas engine, a dual-fuel engine or a multi-fuel engine. Combustion of liquid and / or gaseous fuels in such engines is possible not only by auto-ignition or forced ignition.

[0003] The internal combustion engine may be a longitudinally scavenged two-stroke engine.

[0004] The term internal combustion engine also refers to large engines that can be operated in Otto mode, characterized by spark ignition of a fuel, as well as in Diesel mode, characterized by autoignition of a fuel, or a mixture of the two. Additionally, the term internal combustion engine includes certain dual-fuel engines and large engines in which autoignition of one fuel is used in favor of spark ignition of another fuel.

[0005] Preferably, the engine speed is below 800 RPM, especially for four-stroke engines, and more preferably below 200 RPM, especially for two-stroke engines, which indicates a low speed engine designation.

[0006] The fuel may be diesel or marine diesel, or heavy fuel oil, or an emulsion, or a slurry, or methanol, or ethanol, and gases such as liquefied natural gas (LNG) or liquid petrol gas (LPG).

[0007] Further possible fuels that could be added to the requirements are liquefied biogas (LBG), biological fuels (e.g. oil made from algae or seaweed), ammonia, hydrogen, synthetic fuels from CO2 (e.g. made by power-to-gas or power-to-liquids). [Background technology]

[0008] Large ships, especially those used for transporting cargo, are usually powered by internal combustion engines, specifically diesel and / or gas engines, mainly two-stroke cross-head engines.

[0009] In a reciprocating piston combustion engine, the compression ratio, i.e., the ratio between the maximum and minimum volumes of the cylinder and combustion chamber in an internal combustion engine, is an important parameter for combustion, thermal efficiency, and emissions. The compression ratio is typically selected to produce the best engine performance. High-load engine performance is often the most relevant consideration for this selection. For optimal performance throughout the operating range, a variable compression ratio would be desirable, but due to the complications associated with such a system, a compromise is usually made by providing a constant compression ratio.

[0010] EP 2687707 A2 discloses a large reciprocating piston combustion engine including a control device for controlling the compression ratio of the reciprocating piston combustion machine.

[0011] EP 3805538A1 discloses a variable compression device for changing the compression ratio of an engine, including a crosshead pin connected to a piston rod, a fluid chamber provided inside the crosshead pin, in which the piston rod is moved in a direction to increase the compression ratio by supplying pressurized working fluid into the fluid chamber, and a pump increases the pressure of the working fluid.

[0012] The Variable Compression Ratio (VCR) system allows continuous adjustment of the compression ratio by means of a hydraulic cylinder located in the crosshead pin to move the piston rod vertically. The compression ratio can be adjusted during normal engine operation. The adjustment allows optimization of performance at part load without compromising performance at high / full load. In the case of dual-fuel engines, the compression ratio can be optimized separately for each fuel mode (high compression ratio for diesel mode, low compression ratio for gas mode). Optimization of the compression ratio according to operating conditions (scavenging air temperature, methane number of fuel gas, wave load, etc.) is possible.

[0013] Low leakage from the hydraulic chamber / cylinder is important for the continuous and reliable operation of a hydraulic VCR system. Besides cylinder clearance, oil viscosity also plays a key role in leakage. Oil viscosity is highly dependent on temperature, therefore, the lower the temperature of the oil in the fluid chamber of a VCR system, the less leakage the VCR chamber will have.

[0014] Piston cooling oil that is heated within the piston and expelled from the piston rod through the crosshead pin can heat the hydraulic oil in the crosshead pin and fluid chamber. [Prior art documents] [Patent documents]

[0015] [Patent Document 1] European Patent No. 2687707A2 [Patent Document 2] European Patent No. 3805538A1 Summary of the Invention [Problem to be solved by the invention]

[0016] The object of the present invention is to avoid the drawbacks of the prior art and, in particular, to provide an internal combustion engine and a method for operating the same which allows for continuous and reliable operation of a VCR system. [Means for solving the problem]

[0017] The object is achieved by an internal combustion engine and a method for operating an internal combustion engine according to the independent claims.

[0018] The internal combustion engine has at least one cylinder. Preferably, the internal combustion engine is a large marine engine including at least one cylinder with an internal diameter of at least 200 mm. The internal combustion engine may be a low pressure fuel gas engine or a dual fuel engine with.

[0019] The internal combustion engine has at least one piston movably arranged in a cylinder, and for each cylinder, the internal combustion engine further comprises a rotatably arranged crankshaft, the pistons being connected in each case via a piston rod to a crosshead, to which a crosshead pin is connected, and in each case, the crosshead being connected to the crankshaft via a connecting rod for driving the crankshaft.

[0020] The engine is provided with a variable compression ratio device for varying the compression ratio of the engine. The variable compression ratio device allows the volume above the piston at top dead center to be varied.

[0021] The variable compression ratio device includes a fluid chamber disposed inside the crosshead pin, in which a piston rod is movable relative to the bottom of the fluid chamber, and movement can be induced by supplying pressurized hydraulic fluid, such as hydraulic oil, into and out of the fluid chamber.

[0022] An internal combustion engine may include a pumping device for transporting working fluid into and out of the fluid chamber to vary the compression ratio.

[0023] Typically, the piston rod may include an end portion having a larger diameter at the end of the piston rod near the crosshead pin. The outer peripheral surface of the lower end portion of the piston rod near the crosshead pin may protrude radially outward, such that the diameter of the end portion is larger than the diameter of the intermediate portion of the piston rod.

[0024] The hydraulic fluid may be introduced into a fluid chamber below an end portion of the piston rod near the crosshead pin, and the end portion may include a sealing to retain the hydraulic fluid below the piston rod.

[0025] At the highest compression ratio, the enlarged portion of the end portion of the piston rod may abut against an upper abutment member, for example an upper abutment surface of the fluid chamber. At the lowest compression ratio, the piston rod may abut against the bottom of the fluid chamber.

[0026] The piston rod includes a cooling channel formed inside the piston rod and extending in the direction of piston stroke for guiding a cooling fluid.

[0027] The crosshead pin comprises at least one flow path for guiding a cooling fluid, e.g., cooling oil, to be supplied to at least one of the first cooling channels and at least one second flow path for guiding a cooling fluid to be discharged from at least one of the second cooling channels.

[0028] The first flow path is located within a first distance to a bottom surface defined by a bottom of the fluid chamber, and the second flow path is located within a second distance to the bottom surface, the first and second distances being measured in the same direction. The first distance is shorter than the second distance such that the first flow path is located between the second flow path and the bottom surface in the stroke direction. Preferably, the bottom of the fluid chamber is flat, and the bottom surface includes the bottom of the fluid chamber such that there is only one consistent fluid chamber between the piston rod and the bottom.

[0029] Thus, the first flow path has a shorter distance to any working fluid that may be contained within the fluid chamber than the second flow path.

[0030] The first flow path comprises a plurality of first channels, the plurality of first channels being preferably uniformly arranged within a first cross section of the crosshead pin and parallel to the bottom surface.

[0031] The first flow path is for supplying cooling fluid into the piston rod, while the second flow path is for exhausting the cooling fluid. Typically, the cooling fluid delivered through the first flow path is cooler than the cooling fluid delivered through the second flow path. The first flow path defines a cooling surface that can shield the working fluid in the fluid chamber from the second flow path. Thus, warming of the working fluid, such as hydraulic oil, contained in the fluid chamber by the cooling fluid heated in the piston and exhausted from the piston rod through the second flow path is reduced or even prevented. Because the working fluid maintains its temperature, the risk of leaking the working fluid is reduced, and the compression ratio can be controlled very precisely.

[0032] The internal combustion engine may include a further pumping device for conveying cooling fluid into the first flow path and out of the second flow path.

[0033] The second flow path may include at least one second channel disposed within a second cross section of the crosshead pin parallel to the bottom surface, and may include a plurality of second channels, preferably evenly spaced within the second cross section.

[0034] The first flow path can include a first number of first channels and the second flow path can include a second number of second channels. The first number can be greater than the second number. The greater number of channels can be more evenly distributed to optimize the shielding effectiveness of the first flow path.

[0035] The diameter of the first channel may be smaller than the diameter of the second channel.

[0036] The channels preferably have a circular cross section, or the axial diameter of at least a first channel may be smaller than the axial diameter of a second channel.

[0037] A constant velocity of cooling fluid guided through a small diameter channel can be uniformly distributed across the cross section of the crosshead pin. The uniform distribution is particularly advantageous for the incoming cooling fluid because it insulates the outgoing cooling fluid from heat.

[0038] The diameter of the second channel for the outgoing cooling fluid may be chosen to be larger.

[0039] The distance between the first channels may be shorter than the distance between the second channels. The first flow path having the short distance between the first channels forms a shielding surface containing a well-distributed cooling fluid.

[0040] A first flow path comprising a large number of first channels having small diameters and spaced a short distance apart provides a homogeneous, and therefore effective, shielding surface.

[0041] The diameter of the first channel may be between 5 mm and 50 mm, preferably between 10 mm and 15 mm. An excessively small diameter may result in increased hydrodynamic resistance and may be too expensive to manufacture.

[0042] The number of first channels may be between 5 and 30, preferably between 7 and 15. The number may depend on the diameter of the first channels, which is preferably optimized with respect to hydrodynamic resistance and / or manufacturing costs, as well as on the engine size.

[0043] The distance between the first channels may be between 10 mm and 70 mm, preferably between 20 mm and 30 mm.

[0044] This distance corresponds to a wall thickness between channels that provides sufficient stability and easy manufacturing.

[0045] This distance may depend on the diameter of the first channel, which may be optimized with respect to hydrodynamic resistance and / or manufacturing costs, as well as the engine size.

[0046] The crosshead pin may include a splitter ring.

[0047] The splitter ring may be arranged fixedly relative to the crosshead pin, in particular above or within the fluid chamber.

[0048] The splitter ring may be positioned to define a first annular cavity in fluid communication with at least one cooling channel for supplying a cooling fluid to the piston rod, and the splitter ring may be positioned such that the first annular cavity is in fluid communication with the first flow path.

[0049] The splitter ring is positioned to define a second annular cavity in fluid communication with the at least one cooling channel for exhausting cooling fluid from the piston and in fluid communication with the second flow path.

[0050] The first and second annular cavities are disposed around the piston rod, preferably around an end portion of the piston rod.

[0051] The first and second annular cavities may be fluid-tightly separated from one another, and exchange between the first and second annular cavities must be inhibited or prevented.

[0052] The first annular cavity has a shorter distance to the bottom of the fluid chamber than the second annular cavity.

[0053] The splitter ring separates the incoming and outgoing cooling fluids and prevents mixing of the incoming and outgoing cooling fluids. The incoming cooling fluid, which typically has a lower temperature than the outgoing cooling fluid from the piston rod, can insulate the outgoing cooling fluid from the heat that forms the working fluid contained in the fluid chamber below the piston rod.

[0054] At least one first sealing member may be disposed on an outer peripheral surface of the end portion of the piston rod, and may be provided, at least in part, by a portion of the piston rod having an enlarged diameter and projecting radially outward.

[0055] The first annular cavity may be bounded in the stroke direction by a first sealing member on a lower side closer to the bottom of the fluid chamber and by a splitter ring on an upper side.

[0056] Additionally, a second sealing member may be disposed on the outer peripheral surface of the end portion of the piston rod, and may be provided, at least in part, by a portion of the piston rod having an enlarged diameter and projecting radially outward.

[0057] The second annular cavity may be bounded on a lower side closer to the bottom of the fluid chamber by a splitter ring and on an upper side by a second seal member.

[0058] The first and / or second sealing members may provide a sliding ear face between the piston rod and the crosshead pin.

[0059] The pair of first and second seal members may be spaced apart from each other in the stroke direction of the piston rod, and the first and second seal members are preferably arranged on the outer peripheral surface of the large diameter end portion of the piston rod.

[0060] An annular groove may be formed between the first seal member and the second seal member, in which the exchange of cooling fluid takes place.

[0061] At maximum compression ratios, where the piston rod is forced away from the bottom of the fluid chamber, most of the annular groove is used for the incoming cooling fluid.

[0062] At minimum compression ratio, when the piston rod is closest to the bottom of the fluid chamber, the majority of the annular groove is used to return the cooling fluid.

[0063] For higher compression ratios, the first annular cavity has a smaller axial extent than for lower compression ratios.

[0064] Similarly, for higher compression ratios, the second annular cavity has a larger axial extent than for lower compression ratios.

[0065] The splitter ring may include a sealing member that contacts the outer surface of the piston rod within the annular groove.

[0066] The splitter ring may include at least two half rings, or four quarter rings, preferably threaded together.

[0067] The splitter ring may be radially pressed against the wall of the fluid chamber and / or axially pressed into a groove or step in or above the fluid chamber, and the splitter ring may be prevented from axial movement, preferably toward the bottom of the fluid chamber, by the abutment surface of the groove or step.

[0068] The splitter ring may be secured by a locking device, e.g. a cylindrical spring element, to prevent rotational and / or axial movement.

[0069] The splitter ring may be prevented from axial movement, preferably away from the bottom of the fluid chamber, by the abutment surface of the spring element.

[0070] The piston rod may comprise at least one supply channel for supplying cooling fluid into the cooling channel and / or may comprise at least one exhaust channel for exhausting cooling fluid from the cooling channel.

[0071] Preferably, the supply channel is in fluid communication with the first annular cavity and / or the exhaust channel is in fluid communication with the second annular cavity defined by the splitter ring.

[0072] Preferably, the supply channel has a shorter distance to the bottom of the fluid chamber than the exhaust channel.

[0073] Thus, the first flow path, the first annular chamber, and the supply channel form a supply system, and the second flow path, the second annular chamber, and the discharge channel form a discharge system, wherein the supply system is positioned at a distance closer to the bottom surface than the discharge system.

[0074] The working fluid is therefore completely insulated from the heat of the exiting cooling fluid by the supply system carrying the cooler cooling fluid.

[0075] The internal combustion engine may include at least one first knee lever connected to the crosshead pin for providing and / or releasing cooling fluid, and the first knee lever may include a tube fluidly connected to the first flow path and the second flow path.

[0076] Alternatively, or in addition, the internal combustion engine may include at least one second knee lever connected to the crosshead pin for providing and / or releasing hydraulic fluid, and the second knee lever may include at least one tube fluidly connected to the fluid chamber.

[0077] According to the invention, a method for operating the above-mentioned internal combustion engine comprises the following steps:

[0078] A hydraulic fluid under pressure is provided within the fluid chamber within which the piston rod is movable relative to a bottom of the fluid chamber.

[0079] When hydraulic fluid is supplied to the fluid chamber, the piston rod moves upward, away from the bottom of the fluid chamber, to increase the compression ratio.

[0080] The piston is cooled by directing a cooling fluid through cooling channels disposed within the piston rod.

[0081] A cooling fluid is supplied to at least one of the cooling channels through at least one first flow path in the crosshead pin, and the cooling fluid is discharged from at least one of the cooling channels through at least one second flow path in the crosshead pin.

[0082] The supplied cooling fluid insulates the working fluid from the heat of the exhausted cooling fluid.

[0083] Shielding can be achieved by the discharged cooling fluid being guided at a greater distance relative to the working fluid in the fluid chamber than the supplied cooling fluid.

[0084] A cooling fluid may be supplied to at least one of the cooling channels in a region between the bottom surface and a region where the cooling fluid exits at least one of the cooling channels.

[0085] The working fluid may be maintained at a temperature below 70°C, preferably below 55°C, more preferably below 45°C.

[0086] The piston rod can be moved relative to the bottom of the fluid chamber by supplying hydraulic fluid into the fluid chamber or by draining hydraulic fluid from the fluid chamber.

[0087] According to the present invention, a crosshead pin for an internal combustion engine as described above comprises a fluid chamber for guiding a piston rod movable relative to a bottom of the fluid chamber, the fluid chamber being capable of receiving a working fluid.

[0088] The crosshead pin includes at least one first flow path for guiding cooling fluid to be supplied to at least one of the cooling channels of the piston rod, and at least one second flow path for guiding cooling fluid to be discharged from at least one of the cooling channels of the piston rod.

[0089] The first flow path is disposed within a first distance to a bottom surface defined by the bottom of the fluid chamber, and the second flow path is disposed within a second distance to the bottom surface, the first distance being closer than the second distance. The first flow path comprises first channels preferably evenly spaced within a first cross section of the crosshead pin parallel to the bottom surface.

[0090] The invention will now be further explained in the following examples with the aid of the figures, in which like reference numbers indicate functionally corresponding features. [Brief explanation of the drawings]

[0091] [Figure 1] 1 is a schematic diagram of an internal combustion engine. [Figure 2] FIG. 1 is a schematic diagram of a variable compression ratio device. [Figure 3] FIG. 2 is a further schematic diagram of a variable compression ratio device. [Figure 4] FIG. 1 is a schematic perspective view of a crosshead pin. [Figure 5] FIG. 1 is a schematic partial cross-sectional view of a crosshead pin. [Figure 6] FIG. 1 is a schematic partial cross-sectional view of a crosshead pin and a piston rod. [Figure 7] FIG. 10 is a further schematic partial cross-sectional view of the crosshead pin. [Figure 8] Half-section view of the crosshead pin containing the piston rod in two different positions. DETAILED DESCRIPTION OF THE INVENTION

[0092] FIG. 1 shows a schematic diagram of an internal combustion engine 100 having a cylinder 1. The engine 100 has a piston 6 movably disposed within the cylinder. The piston 6 is connected via a piston rod 7 to a crosshead pin 11 disposed within a crosshead 8. The crosshead 8 is connected to a crankshaft 2 via a connecting rod 9 for driving the crankshaft 2.

[0093] The engine 100 is equipped with a variable compression ratio device 10 for varying the compression ratio of the engine.

[0094] 2, the variable compression ratio device 10 includes a fluid chamber 12 disposed inside a crosshead pin 11. The piston rod 7 is movable relative to a bottom 13 of the fluid chamber 12 when pressurized working fluid is supplied into the fluid chamber 12.

[0095] A knee lever 28 is connected to the crosshead pin 11 for providing and / or releasing hydraulic fluid.

[0096] The end portion 44 of the piston rod 7 has an enlarged radial diameter compared to the middle portion 45 of the piston rod.

[0097] The overall length 32 of the piston rod 7 and crosshead pin 11 in the stroke direction varies according to the separation distance 41 between the stepped surface 42 of the end portion 44 of the piston rod 7 and the stepped surface 43 of the crosshead pin 11 in the stroke direction, which here is the upper abutment surface of the fluid chamber 12.

[0098] FIG. 3 shows a further schematic diagram of the variable compression ratio device 10.

[0099] The piston rod 7 is provided with cooling channels 14a, 14b for guiding cooling fluid to the piston 6. The cooling fluid may be provided by a knee lever 27 (see FIG. 2) connected to the crosshead pin 11.

[0100] The crosshead pin 11 comprises a first flow path 15 for guiding cooling fluid to be supplied to the first cooling channel 14a and at least one second flow path 16 for guiding cooling fluid to be discharged from the second cooling channel 14b.

[0101] The first flow path 15 is located within a first distance d1 to a bottom surface 17 that includes the bottom 13 of the fluid chamber 12, and the second flow path 16 is located within a second distance d2 measured in the same direction to the bottom surface 17. The first distance d1 is shorter than the second distance d2.

[0102] As can be seen in Figure 4, the first flow path 15 comprises a plurality of first channels 18 evenly spaced within a first cross section 19 of the crosshead pin 11 parallel to the bottom surface 17. The first channels 18 open into the fluid chamber 12. A first seal member 45 (see Figure 6) on the piston rod 7 prevents the cooling fluid from mixing with the working fluid.

[0103] 5 shows a schematic partial cross-sectional view of the crosshead pin 11. The second flow path 16 comprises a plurality of second channels 20 disposed within a second cross section 21 of the crosshead pin 11 parallel to the bottom surface 17. A first number of the first channels 18 is greater than a second number of the second channels 20.

[0104] The diameter D1 of the first channel 18 is smaller than the diameter D2 of the second channel 20.

[0105] The distance d3 between the first channels 18 is less than the distance d4 between the second channels 20.

[0106] Cooling fluid is supplied to at least one of the cooling channels 14a (see FIG. 3) in a region 29 between the bottom surface 17 and a region 30 where the cooling fluid exits the cooling channel 14b (see FIG. 3).

[0107] FIG. 6 shows a schematic partial cross-sectional view of the crosshead pin 11 and the piston rod 7.

[0108] The piston rod end portion 44 has an enlarged diameter and is provided with a first seal member 45 and a second seal member 46 provided by portions of the piston rod 7 that project radially outwardly.

[0109] The crosshead pin 11 is provided with a splitter ring 22 .

[0110] The splitter ring 22 defines a first annular cavity 23 below the splitter ring 22. The first annular cavity 23 is in fluid communication with the cooling channel 14a for supplying cooling fluid to the piston 6 via a supply channel 25. The first annular cavity 23 is also in fluid communication with the first flow path 15.

[0111] The splitter ring 22 also defines a second annular cavity 24 above the splitter ring 22. The second annular cavity 24 is in fluid communication with at least one cooling channel 14b for exhausting cooling fluid from the piston rod 7 via an exhaust channel 26. The second annular cavity 24 is also in fluid communication with the second flow path 16.

[0112] The splitter ring 22 provides a fluid-tight separation between the first annular cavity 23 and the second annular cavity 24 .

[0113] The first annular cavity 23 is disposed below the second annular cavity 24 and has a shorter distance to the bottom 13 of the fluid chamber 12 than the second annular cavity 24 .

[0114] The first annular cavity 23 is bounded in the stroke direction by the first sealing member 45 on the lower side, closer to the bottom 13 , and by the splitter ring 22 on the upper side.

[0115] The second annular cavity 24 is bounded in the stroke direction by the second seal member 46 on the upper side and by the splitter ring 22 on the lower side.

[0116] FIG. 7 shows a further schematic partial cross-sectional view of the crosshead pin 11.

[0117] The splitter ring 22 is fixed to the crosshead pin 11 by a locking device, in this case a cylindrical spring element 31 .

[0118] FIG. 8 is a half-section view of the crosshead pin 11 containing the piston rod 7 in two different positions.

[0119] In the left-hand illustration, the piston rod 7 is in its uppermost position, which corresponds to the maximum possible compression ratio. The second annular cavity 24 above the splitter ring 22 has its maximum axial extent.

[0120] In the right-hand illustration, the piston rod 7 is in its lowest position, which corresponds to the smallest possible compression ratio. The first annular cavity 23 below the splitter ring 22 has its maximum axial extent.

[0121] In either case, the second annular cavity 24 is in fluid contact with the discharge channel 26 and the second channel 20 of the second flow path 16, while the first annular cavity 23 is in fluid contact with the supply channel 25 and the first channel 18 of the first flow path 15.

[0122] The supply system comprising the first flow path 15, the first annular cavity 23 and the supply channel 25 is arranged below the discharge system comprising the second flow path 16, the second annular cavity 24 and the discharge channel 26 for all axial positions of the piston rod 7.

[0123] The incoming cooling fluid therefore shields the working fluid contained in the fluid chamber 12 from the heat of the exiting cooling fluid for all axial positions of the piston rod 7 . [Explanation of symbols]

[0124] 1 cylinder 2 crankshaft 6 pistons 7 Piston rod 8 Crosshead 9 connecting rod 10 Variable Compression Device 11 Crosshead Pin 12 Fluid chamber 13 Bottom 14a, 14b Cooling channels 15 First flow path 16 Second flow path 17 Bottom surface 18 First Channel 19 Cross Section 20 Second Channel 21 Second cross section 22 Splitter Ring 23 First annular cavity 24 Second annular cavity 25 1 supply channel 26 Discharge Channel 27, 28 Knee lever 29 areas 30 areas 31 Oil Splitter Locking Device 32 length 41 distance 42 stepped surface 43 Stepped Surface 44 End part 45 first seal member 46 Second sealing member 100 Internal combustion engine

Claims

1. An internal combustion engine (100) having at least one cylinder (1), i.e. a large marine engine including at least one cylinder (1) having an internal diameter of at least 200 mm, At least one piston (6) movably disposed within the cylinder (1), A crankshaft (2) is rotatably arranged, the piston (6) is connected to a crosshead (8) through a piston rod (7), a crosshead pin (11) is connected to the piston rod (7), and the crosshead (8) is connected to the crankshaft (2) through a connecting rod (9) for driving the crankshaft (2), the internal combustion engine comprises a variable compression ratio device (10) for varying the compression ratio of the internal combustion engine (100); The variable compression ratio device (10) comprises a fluid chamber (12) arranged inside the crosshead pin (11), and in the fluid chamber (12), the piston rod (7) is movable relative to a bottom (13) of the fluid chamber (12) by supplying a pressurized working fluid into the fluid chamber (12); the piston rod (7) is provided with cooling channels (14a, 14b), an internal combustion engine (100) in which the crosshead pin (11) comprises at least one first flow path (15) for guiding a cooling fluid to be supplied to at least one of the cooling channels (14a) and at least one second flow path (16) for guiding a cooling fluid to be discharged from at least one of the cooling channels (14b), the first flow path (15) is located within a first distance (d1) to a bottom surface (17) defined by the bottom (13) of the fluid chamber (12), and the second flow path (16) is located within a second distance (d2) to the bottom surface (17), the first distance (d1) being shorter than the second distance (d2), so that in the stroke direction, the first flow path (15) is located between the second flow path (16) and the bottom surface (17) defined by the bottom (13) of the fluid chamber (12); 1. An internal combustion engine (100), wherein the first flow path (15) comprises a plurality of first channels (18) evenly arranged within a first cross section (19) of the crosshead pin (11) parallel to the bottom surface (17).

2. 2. The internal combustion engine of claim 1, wherein the second flow path (16) comprises at least one channel (20) disposed within a second cross section (21) of the crosshead pin (11) parallel to the bottom surface (17).

3. the first flow path (15) comprises a first number of first channels (18), and the second flow path (16) comprises a second number of second channels (20); the first number is greater than the second number; The diameter (D1) of the first channel (18) is smaller than the diameter (D2) of the second channel (20); and a distance (d3) between the first channels (18) is shorter than a distance (d4) between the second channels (20); 3. An internal combustion engine according to claim 1 or 2.

4. the diameter (D1) of the first channel is between 5 mm and 50 mm; the number of first channels is between 5 and 30; and At least one of: the distance (d3) between the first channels is between 10 mm and 70 mm; 2. The internal combustion engine according to claim 1.

5. The crosshead pin (11) is provided with a splitter ring (22), the splitter ring (22) is positioned to define a first annular cavity (23) in fluid communication with at least one cooling channel (14a) for supplying a cooling fluid to the piston (6) and in fluid communication with the first flow path (15); and the splitter ring (22) is positioned to define a second annular cavity (24) in fluid communication with at least one cooling channel (14b) for exhausting cooling fluid from the piston (6) and in fluid communication with the second flow path (16); the first annular cavity (23) and the second annular cavity (24) are separated from each other; the first annular cavity (23) has a shorter distance to the bottom (13) of the fluid chamber (12) than the second annular cavity (24); 2. The internal combustion engine according to claim 1.

6. 6. The internal combustion engine of claim 5, wherein the splitter ring (22) includes at least two half rings.

7. 6. The internal combustion engine of claim 5, wherein the splitter ring (22) is pressed axially into a groove or step within or above the fluid chamber (12) and / or is secured by a splitter ring locking device to prevent at least one of rotational and axial movement.

8. the piston rod (6) comprises at least one supply channel (25) for supplying cooling fluid into the cooling channel (14a) and at least one discharge channel (26) for discharging cooling fluid from the cooling channel (14b); 2. An internal combustion engine according to claim 1, wherein the supply channel (25) has a shorter distance to the bottom (13) of the fluid chamber (12) than the discharge channel (26).

9. 2. The internal combustion engine of claim 1, wherein the internal combustion engine comprises at least one of at least one knee lever connected to the crosshead pin for providing and / or releasing the cooling fluid, and at least one knee lever connected to the crosshead pin for providing and / or releasing the working fluid.

10. 2. A method for operating an internal combustion engine (100) according to claim 1, comprising: - providing a pressurized working fluid in a fluid chamber (12) in which the piston rod (7) is movable relative to the bottom (13) of the fluid chamber (12); - cooling said piston (6) by directing a cooling fluid through cooling channels (14a, 14b) in said piston rod (7); - supplying said cooling fluid to at least one of said cooling channels (14a) through at least one first flow path (15) in said crosshead pin (11) and discharging said cooling fluid from at least one of said cooling channels (14b) through at least one second flow path (16) in said crosshead pin (11); Including, - in the stroke direction, the first flow path (15) is arranged between the second flow path (16) and the bottom surface (17) defined by the bottom (13) of the fluid chamber (12); - the supplied cooling fluid insulates the working fluid from the heat of the discharged cooling fluid.

11. The method of claim 10, wherein the working fluid maintains a temperature below 70°C.

12. 11. The method according to claim 10, comprising the step of moving the piston rod (7) relative to the bottom (13) of the fluid chamber (12) by supplying or discharging working fluid into or from the fluid chamber (12).

13. a fluid chamber (12) for receiving a piston rod (7) movable relative to a bottom (13) of said fluid chamber (12); 2. A crosshead pin for an internal combustion engine (100) according to claim 1, comprising at least one first flow path (15) for guiding a cooling fluid to be supplied to at least one of the cooling channels (14a) of the piston rod (7) and at least one second flow path (16) for guiding a cooling fluid to be discharged from at least one of the cooling channels (14b) of the piston rod, a first flow path (15) arranged within a first distance (d1) to a bottom surface (17) defined by the bottom (13) of the fluid chamber (12), and a second flow path (16) arranged within a second distance (d2) to the bottom surface (17), the first distance (d1) being shorter than the second distance (d2), such that in the stroke direction, the first flow path (15) is arranged between the second flow path (16) and the bottom surface (17) defined by the bottom (13) of the fluid chamber (12), and the first flow path (15) includes first channels (18) evenly distributed within a first cross section (19) of the crosshead pin (11) parallel to the bottom surface (17).

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