Piston Ring

Abstract

To provide a piston ring 100.SOLUTION: The piston ring 100 comprises a ring section 1 and a lock section 2 with a male locking end 3 and a female locking end 4. The male locking end 3 comprises a tongue 5, and the female locking end 4 comprises a recess 6, so that the tongue 5 is insertable into the recess 6. The recess 6 is opened towards an outside 44 of the piston ring 100 and is arranged between a first shank 41 and a second shank 42. A maximal width 13 of the ring section 1 is smaller than the sum of a maximal width 15 of at least a circumferentially extending part 18 of the tongue 5 and a maximal width 16 of at least a first circumferentially extending part 17 of the first shank 41.SELECTED DRAWING: Figure 4

Description

Technical Field

[0001] The present invention relates to a piston ring for a piston of a reciprocating internal combustion engine as described in the general clause of claim 1, a piston provided with such a piston ring, a reciprocating internal combustion engine provided with such a piston, and a method for manufacturing a piston ring.

[0002] The present invention preferably relates to an internal combustion engine such as a large ship or a ship engine, or a stationary engine having a cylinder with an inner diameter of at least 200 mm.

Background Art

[0003] The engine is preferably a two-stroke engine or a two-stroke crosshead type engine. The engine can be a diesel engine or a gas engine, a dual fuel or multi-fuel engine. Combustion of liquid and / or gaseous fuel in such an engine is possible by either self-ignition or forced ignition.

[0004] The internal combustion engine can be a longitudinally scavenged two-stroke engine.

[0005] The term internal combustion engine also refers to large engines that can operate not only in diesel mode characterized by self-ignition of fuel, but also in Otto mode characterized by forced ignition of fuel, or a mixture of the two. Furthermore, the term internal combustion engine specifically includes dual fuel engines and large engines in which self-ignition of one fuel is used for forced ignition of another fuel.

[0006] The engine speed is preferably less than 800 RPM, particularly in the case of a four-stroke engine, and more preferably less than 200 RPM, particularly in the case of a two-stroke engine, indicating that it is designated as a low-speed engine.

[0007] Fuels can be not only diesel oil or marine diesel oil, heavy fuel oil, emulsions, slurries, methanol, or ethanol, but also gases such as liquefied natural gas (LNG), liquefied petroleum gas (LPG), natural gas (NG), and petrol gas (PG).

[0008] Another possible fuel that can be added upon request is liquefied biogas (LBG), biofuels (e.g., oils made from algae or seaweed), ammonia, hydrogen, and synthetic fuels made from CO2 (e.g., made by Power-To-Gas or Power-To-Liquid).

[0009] Large ships, specifically vessels for transporting goods, are usually driven by internal combustion engines, specifically diesel and / or gas engines, mainly two-stroke cross-head type engines.

[0010] The pistons of reciprocating piston internal combustion engines, specifically dual-fuel or Otto-cycle type reciprocating piston internal combustion engines, are equipped with piston rings that are fixed in the grooves of the pistons and serve to seal the combustion chamber from the outside.

[0011] Piston rings used in reciprocating piston internal combustion engines, especially those of the two-stroke large dual-fuel or Otto-cycle design, usually have an essentially rectangular cross-section. Due to the special shape of the running surface of the piston ring, there may be a slight deviation from the rectangle in the area of the running surface. The outer-facing side of the piston ring can be warped.

[0012] The conventionally measured axial height of a piston ring is usually smaller than the radial cross-sectional dimension, i.e., the difference between the outer diameter and the inner diameter. General values of the axial height according to the nominal diameter of the piston ring are listed, for example, in DIN34110.

[0013] Such a piston ring is known, for example, from German Patent No. 197 20 779 C1.

[0014] The piston ring locking part shown in Swiss Patent No. 229278 or European Patent No. 1655522 B1 can be formed by two locking ends of the piston. The tongue is formed on the male locking end of the piston ring, and the recess is formed on the female locking end. The recess extends over a part of the radial width and the axial height of the piston ring.

[0015] The tongue and the recess are designed and arranged so that they can slide relative to each other in the circumferential direction of the piston ring. By the tongue, the dividing line of the area of the tongue is interrupted in both the axial and radial directions. Therefore, this design is also called an "airtight" locking part.

[0016] The dimensions of the tongue and the recess are typically manufactured so that the gap between the tongue and the recess is between 0.05 and 0.1 mm, which is about the same size as the warp or even larger.

[0017] The contact line between the piston ring and the cylinder is constantly defined by the maximum extension line of the warp. The recess is open outward and is arranged facing the tongue so that the piston ring can be locked.

[0018] When pressure is generated from the inside of the piston ring, the inner part of the piston ring locking part, for example, the locking end with the recess, presses against the outer part of the piston ring locking part, for example, the locking end with the tongue.

[0019] When there is pressure in the combustion chamber and the piston ring is axially pressed against the piston groove, usually pressure is generated from the inside.

[0020] However, due to the pressure from the inside of the piston ring, the locking end portion having a recess may cause the maximum extension line of the warp of the tongue portion of the other locking end portion to no longer be the radially outermost portion of the piston ring locking portion, but the locking end portion having a recess may move radially outward to such an extent that it contacts the cylinder.

[0021] In this case, the cylinder wall may be damaged by the sharp edge of the recess.

Prior Art Documents

Patent Documents

[0022]

Patent Document 1

Patent Document 2

Patent Document 3

Summary of the Invention

Problems to be Solved by the Invention

[0023] The present invention is based on the task of avoiding known drawbacks and realizing sufficient sealing performance and long-life durability not only for the piston ring but also for the cylinder liner, providing a piston ring, a piston provided with such a piston ring, a reciprocating internal combustion engine provided with such a piston, and a method for manufacturing a piston ring of the above type.

Means for Solving the Problems

[0024] This problem is solved by a piston ring for a piston of a reciprocating internal combustion engine according to claim 1.

[0025] The piston ring includes a ring section and a locking section.

[0026] The piston ring can be a single part having a core made of a cast iron material.

[0027] The ring section has a height in the axial direction and a maximum width in the radial direction. The cross-section can be rectangular, and as a result, the maximum width corresponds to a constant width of the rectangle.

[0028] The locking section includes a male locking end and a female locking end.

[0029] The male locking end includes a tongue extending in the circumferential direction, and the female locking end has a recess extending in the circumferential direction such that the tongue can be inserted into the recess.

[0030] The recess is sized and shaped to receive the tongue in a sealed and slidable manner. The tongue can slide circumferentially within the recess to allow for the expansion and contraction of the piston ring.

[0031] The tongue has a maximum width in the radial direction that is narrower than the maximum width of the ring section, and a height in the axial direction that is lower than the height of the ring section.

[0032] Preferably, the tongue has a maximum width that is 50% to 90% of the maximum width of the ring section, and a height in the axial direction that is 20% to 80% of the height of the ring section.

[0033] The tongue has a sliding surface facing radially inward over the circumferential length and the height of the tongue. The normal to the sliding surface facing radially inward is directed radially inward, i.e., towards the center of the piston ring.

[0034] The tongue further has a sliding surface in the axial direction over the circumferential length and the radial width. The normal to the sliding surface in the axial direction is directed axially. When combined with each groove of the piston, the normal to the sliding surface in the axial direction can be directed towards the combustion chamber.

[0035] The recess is open towards the outside of the piston ring and is disposed between a first shank and a second shank. The shanks of the female locking end basically form an L-shape in the cross-sectional view.

[0036] When combined with each groove of the piston, the recess can be opened in a direction facing away from the combustion chamber, i.e., downwardly toward the piston.

[0037] The radial width of the first leg is narrower than the width of the ring section. The first leg provides a guiding surface facing radially outward. The outward-facing guiding surface basically corresponds to the sliding surface facing inward of the tongue.

[0038] The axial height of the second leg is lower than the height of the ring section. The second leg provides an axial guiding surface. The axial guiding surface basically corresponds to the axial sliding surface of the tongue.

[0039] The maximum width of the ring section is narrower than the sum of the maximum width of at least the circumferentially extending portion of the tongue and the maximum width of at least the first circumferentially extending portion of the first leg.

[0040] Preferably, the maximum width of the ring section is narrower than the sum by 0.01 mm to 0.15 mm, or 0.1% - 0.6%, more preferably 0.17% - 0.5% of the maximum width of the ring section.

[0041] When combined with each groove of the piston, the circumferentially extending portion of the tongue and the first circumferentially extending portion of the first leg overlap.

[0042] The circumferential region of the overlapping locking ends, where the sum of the maximum widths of the locking ends is wider than the maximum width of the piston ring, is called the bridging region. Since the locking ends may move relative to each other, the circumferential length of the bridging region may vary.

[0043] The circumferential length of the bridging region is between 10% and 70% of the circumferential length of the recess and / or the tongue.

[0044] Because the maximum radial width of this bridging region is wider, even when pressure is applied from the inside of the ring, the outermost portion of the locking section is surely held in the same state as when no pressure is applied.

[0045] The difference between the sum of the maximum width of the ring section and the maximum width of the locking end portion of the crosslinked section is equal to or wider than the typical radial space between the locking end portions that overlap in a state where no pressure is applied.

[0046] Therefore, even when the first shin portion is pressed against the tongue portion, the sum of the maximum radial widths of the crosslinked section is wider than the maximum width of the ring section.

[0047] Preferably, the circumferentially extending portion of the tongue portion is not arranged adjacent to the free end portion of the tongue portion, and the circumferentially extending portion of the first shin portion does not overlap with the region adjacent to the free end portion of the tongue portion.

[0048] The free end portion of the tongue portion is the circumferential free end portion.

[0049] Preferably, the circumferentially extending portion of the first shin portion is arranged adjacent to the free end portion of the first shin portion, and the circumferentially extending portion of the tongue portion overlaps with the region adjacent to the free end portion of the first shin portion. The free end portion of the first shin portion is the circumferential free end portion and corresponds to the circumferential free end portion of the female locking end portion.

[0050] In the vicinity of the free end portion of the tongue portion, the sum of the maximum width of the tongue portion and the maximum widths of the respective overlapping portions of the first shin portion should be narrower than or equal to the maximum width of the ring section, and therefore the open end portion of the tongue portion does not form a circumferential edge.

[0051] When pressure is applied from the inside of the piston ring, in the crosslinked region, the radial space between the locking end portions is filled, while in the overlapping region adjacent to the crosslinked region, there is still a radial space between the locking end portions. Therefore, the free end portion of the male locking end portion may have the freedom to bend radially inward. That is, the free end portion of the tongue portion does not form a sharp edge that may damage the liner.

[0052] Preferably, the tongue portion is disposed on the first axial side of the piston ring, and the recess is open toward the first axial side. When disposed in the groove of the piston, the piston ring in this case is airtight against the pressure from the second axial side of the piston ring, which is opposite to the first side.

[0053] In a preferred embodiment of the piston ring, the outer-facing side surface of the piston ring is warped, and in the region of the locking section, the maximum extension line is disposed on the tongue portion.

[0054] Preferably, the maximum extension line of the warp is axially located at the center of the height of the piston ring or divides the height into one-fourth and three-fourths of the height.

[0055] The maximum extension line of the warp is typically axially located at 25% to 33% of the height of the ring outer shape, measured from the first axial side. The range can extend from 15% to 50%. In addition, the maximum extension line of the warp is axially located so as to run across the male part.

[0056] Alternatively, the maximum extension line of the warp can be axially located at 15% to 50%, preferably 25% to 33%, of the height of the ring outer shape, measured from the second axial side. In this case, when the male locking end portion has only one tongue portion and the female locking end portion has only one recess, the maximum extension line of the warp can run over the recess of the female part.

[0057] The warp, specifically the axial position of the maximum extension line of the warp, defines the axial positions of the maximum width of the ring section and the maximum width of the tongue portion.

[0058] Preferably, the difference between the maximum width of the ring section and the sum of the maximum widths of the locking ends of the cross-linked region is wider than the extension of the warp.

[0059] When pressure is applied from the inside of the piston ring, the guiding surface facing the outside of the female locking end portion presses the sliding surface facing the inside of the male locking end portion.

[0060] If the difference between the sum of the maximum width of the ring section and the maximum width of the locking end of the cross-linked region is wider than the extension of the warp, then at least in the cross-linked region, even when the gap between the locking ends is filled, the second shin part cannot extend further outward than the outermost line of the warp arranged on the tongue part.

[0061] Since the liner still only contacts the outermost line of the warp, there is no risk that the edge of the shin part will damage the liner.

[0062] The portion of the guiding surface facing radially outward of the first shin part extending in the first circumferential direction may be provided with a radially outward protruding part.

[0063] The radial extension of the protruding part can define the difference between the sum of the maximum width of the ring section and the maximum width of the locking end of the cross-linked region. Therefore, the protruding part can be, for example, 0.01 mm to 0.15 mm in radial width, or 0.1% to 0.6% of the maximum width of the ring section.

[0064] Specifically, the protruding part extends circumferentially from the end of the female locking end to 10% to 80% of the circumferential length of the first shin part, preferably up to half of the circumferential length of the first shin part. Preferably, the protruding part extends axially over the entire axial height of the guiding surface facing outward of the first shin part.

[0065] Alternatively or additionally, the portion of the sliding surface facing radially inward of the tongue part extending in the first circumferential direction may be provided with a radially inward protruding part.

[0066] The radial extension of the protruding part can define the difference between the sum of the maximum width of the ring section and the maximum width of the locking end of the cross-linked region. Therefore, the protruding part can be, for example, 0.05 mm to 0.15 mm in radial width, or 0.1% to 0.6% of the maximum width of the ring section.

[0067] The protrusion specifically extends circumferentially over 10% to 100% of the circumferential length of the tongue portion, preferably over at most half of the circumferential length of the tongue portion. Preferably, the protrusion extends axially over the entire axial height of the sliding surface facing radially inward of the tongue portion.

[0068] Preferably, the protrusion is arranged away from the end of the male locking end portion.

[0069] Alternatively or additionally, a recess can be arranged in the second circumferentially extending portion of the guiding surface facing radially outward of the first shin portion.

[0070] Preferably, the recess is arranged circumferentially away from the free end of the female locking end portion.

[0071] This distance away is preferably the circumferential length in the range of 10% to 80% of the circumferential length of the first shin portion.

[0072] Preferably, the recess has a circumferential length of 20% to 90% of the circumferential length of the first shin portion. Preferably, the recess has an axial height extending over the entire axial height of the first shin portion. The recess can have a radial depth, for example, from 0.05 mm to 5 mm, preferably from 0.05 mm to 0.2 mm, or from 0.1% to 0.6% of the maximum width of the ring section.

[0073] The second circumferentially extending portion of the recess is preferably arranged adjacent to the first circumferentially extending portion of the recess with the protrusion, and the first circumferentially extending portion extends from the end of the female locking end portion to 10% to 80% of the circumferential length of the first shin portion.

[0074] The total radial width of the locking end portion of the bridging region can be defined by the radial width of the female locking end portion in the first circumferential region outside the second circumferential region with the recess and the radial width of the male locking end portion of the bridging region.

[0075] The total radial width of the locking ends in the bridging area is wider than the rest of the overlapping area. This can be achieved by the radial protrusions on the first leg in the first circumferential area outside the second circumferential area having the recess, and / or by the radial protrusions on the sliding surface facing radially inwards of the tongue.

[0076] The protrusions on the sliding surface facing radially inwards of the tongue can extend circumferentially across the entire sliding surface facing inwards. This is because, due to the recess, even when pressure is applied from the inside of the piston ring, the free end of the tongue can still bend freely inwards.

[0077] The protrusions on the male locking end and / or the female locking end can be made of the same material as the core of the piston ring.

[0078] Preferably, the protrusions comprise a material with a higher hardness than the hardness in the ring section of the piston ring or the hardness of the core of the piston ring. For example, the core of the piston ring can have a hardness of 220 - 280 HB. The protrusions can include chromium, nickel, and / or ceramic.

[0079] The higher hardness can provide appropriate support to the tongue even when pressure is applied from the inside.

[0080] Alternatively, the protrusions can have a lower hardness than the hardness of the core of the piston ring. The surface of the protrusions will conform better to the corresponding surface, and the corresponding surface will experience less severe cracking and wear. The protrusions can include soft metals, such as aluminum, bronze, non-ferrous metals, mild steel.

[0081] This problem is also solved by the piston ring according to claim 6, preferably the above piston ring.

[0082] The piston ring comprises a ring section and a locking section.

[0083] The ring section has an axial height and a maximum radial width. The cross-section can be rectangular, so that the maximum width corresponds to a constant width of the rectangle, or the piston ring can be warped.

[0084] The locking section comprises a male locking end and a female locking end.

[0085] The male locking end comprises a tongue extending in the circumferential direction, and the female locking end has a recess extending in the circumferential direction such that the tongue can be inserted into the recess.

[0086] The tongue has a maximum radial width narrower than the maximum width of the ring section and an axial height lower than the height of the ring section.

[0087] The tongue has a sliding surface facing radially inwards over the circumferential length and the height of the tongue.

[0088] The tongue further has an axial sliding surface over the circumferential length and the radial width.

[0089] The recess is open towards the outside of the piston ring and is arranged between a first leg and a second leg.

[0090] The radial width of the first leg is narrower than the width of the ring section. The first leg provides a guiding surface facing radially outwards. The guiding surface facing outwards basically corresponds to the sliding surface facing inwards of the tongue.

[0091] The axial height of the second leg is lower than the height of the ring section. The second leg provides an axial guiding surface. The axial guiding surface basically corresponds to the axial sliding surface of the tongue.

[0092] At least a groove extending axially is arranged at the free end of the male locking end.

[0093] Alternatively or additionally, at least one groove is arranged at the female locking end.

[0094] Specifically, the groove extending in the axial direction is arranged at the free end of the female locking end portion, specifically the second shin portion.

[0095] The groove extending in the axial direction can be arranged in the recess.

[0096] The groove extending in the circumferential direction can be arranged on the surface facing outward of the second shin portion.

[0097] Alternatively or additionally, at least one hole, specifically the axial hole of the second shin portion, is arranged at the female locking end portion.

[0098] The described grooves and holes arranged at the locking end portion affect at least one elasticity of the locking end portion. As a result, each locking end portion is prone to break, compress, and / or bend under pressure. Therefore, the risk that the free end of the locking end portion damages the liner of the cylinder is reduced.

[0099] The grooves and / or holes enable the rigidity of the edge of the element to be lower. Therefore, when the end of the female second shin portion contacts the running surface of the liner due to the pressure applied from the inside of the piston ring, the force applied to the edge is dispersed over a wider area, and thus the maximum force is limited.

[0100] Especially when there is a cross-linked region in the overlapping region in a state where the total radial width is wider, the male locking end portion with grooves is more easily bent inward.

[0101] At the same time, the grooves and holes are arranged such that the locking section still guarantees the airtightness of the piston ring.

[0102] This problem is also solved by the piston ring according to claim 7, preferably the above-mentioned piston ring.

[0103] The piston ring comprises a ring section and a locking section.

[0104] The ring section has an axial height and a maximum radial width. The cross-section can be rectangular, so that the maximum width corresponds to a constant width of the rectangle, or the piston ring can be warped.

[0105] The locking section comprises a first and a second locking end, preferably a male locking end and a female locking end.

[0106] The male locking end preferably comprises a tongue extending in the circumferential direction, and the female locking end preferably has a recess extending in the circumferential direction such that the tongue can be inserted into the recess.

[0107] The tongue can have a maximum radial width that is narrower than the maximum width of the ring section and an axial height that is lower than the height of the ring section.

[0108] The tongue can have a sliding surface facing radially inwards over the circumferential length and the height of the tongue. The tongue can further have a sliding surface in the axial direction over the circumferential length and the radial width.

[0109] The recess can be open towards the outside of the piston ring and can be arranged between a first leg and a second leg.

[0110] The radial width of the first leg is preferably narrower than the width of the ring section. The first leg can provide a guiding surface facing radially outwards. The guiding surface facing outwards can basically correspond to the sliding surface facing inwards of the tongue.

[0111] The second leg can have an axial height that is lower than the height of the ring section. The second leg provides a guiding surface in the axial direction. The guiding surface in the axial direction basically corresponds to the sliding surface in the axial direction of the tongue.

[0112] The gas barrier is arranged on at least one of the locking ends, preferably on the tongue, more preferably on the sliding surface facing radially inwards of the tongue and / or on the axial sliding surface of the tongue. The gas barrier at least partially fills the radial and / or axial space existing between the overlapping locking ends without applying any pressure.

[0113] Specifically, the gas barrier can have a height of at most 1 mm, preferably 0.01 - 0.2 mm.

[0114] The height of the gas barrier corresponds to the protrusion of the locking end relative to the level of the locking end adjacent to the barrier.

[0115] The gas barrier can have a circumferential width of 0.5 - 10 mm, preferably 1 - 5 mm and / or 10% - 90% of the circumferential length of the locking end.

[0116] Preferably, the gas barrier has a hardness lower than that of the core of the piston ring. When the diameter of the piston ring changes and the locking ends move relative to each other, the surface of the gas barrier is rubbed and becomes flat. Thus, the surface of the gas barrier conforms to the corresponding surface of the other locking end.

[0117] Preferably, the gas barrier contains or is composed of a corrosion - resistant and / or heat - resistant material.

[0118] The gas barrier can include soft metals such as aluminum, bronze, non - ferrous metals, mild steel.

[0119] The gas barrier can be formed by a layer arranged on the core of the raw material of the piston. The gas barrier can also be formed as a layer arranged in a depression of the core of the raw material of the piston.

[0120] The gas barrier further reduces the flow of gas through the locking section of the piston ring.

[0121] The locking section can be provided with the crosslinked region and the gas barrier as described above. The gas barrier itself can form a protrusion to provide a wider radial width in the crosslinked region. In this case, the gas barrier has two functions. That is, guiding the locking end when pressure is applied from the inside of the piston ring, and reducing the gas flow.

[0122] Alternatively, the gas barrier can be arranged adjacent to the circumferential region of the recess adjacent to the protrusion of the tongue or adjacent to the recess adjacent to the depression.

[0123] This problem is also solved by the piston ring according to claim 8, preferably the above piston ring.

[0124] The piston ring comprises a ring section and a locking section.

[0125] The ring section has an axial height and a maximum radial width. The cross-section can be rectangular, so that the maximum width corresponds to a constant width of the rectangle, or the piston ring can be warped.

[0126] The locking section comprises a male locking end and a female locking end.

[0127] The male locking end comprises a first tongue extending in the circumferential direction, and the female locking end has a first recess extending in the circumferential direction such that the first tongue can be inserted into the recess.

[0128] The first tongue has a maximum radial width narrower than the maximum width of the ring section and an axial height lower than the height of the ring section.

[0129] The first tongue has a sliding surface facing radially inward over the circumferential length and the height of the first tongue.

[0130] The first tongue further has an axial sliding surface over the circumferential length and the radial width.

[0131] The first recess is open towards the outside of the piston ring and is disposed between the first leg portion and the second leg portion.

[0132] The radial width of the first leg portion is narrower than the width of the ring section. The first leg portion provides a guiding surface facing radially outward. The guiding surface facing outward basically corresponds to the sliding surface facing inward of the first tongue portion.

[0133] The axial height of the second leg portion is lower than the height of the ring section. The second leg portion provides an axial guiding surface. The axial guiding surface basically corresponds to the axial sliding surface of the first tongue portion.

[0134] The male locking end portion includes a second tongue portion, and the female locking end portion has a second recess such that the second tongue portion can be inserted into the second recess.

[0135] The second tongue portion has a maximum radial width narrower than the maximum width of the ring section and an axial height lower than half of the height of the ring section.

[0136] The second tongue portion has a sliding surface facing radially inward over the circumferential length and the height of the second tongue portion.

[0137] The second tongue portion has an axial sliding surface over the circumferential length and the radial width of the second tongue portion.

[0138] The second recess is also open towards the outside of the piston ring and is disposed between the third leg portion and the second leg portion.

[0139] The third leg portion has a radial width narrower than the width of the ring section and provides a guiding surface facing radially outward corresponding to the sliding surface facing inward of the second tongue portion.

[0140] The second leg portion provides a second axial guiding surface corresponding to the axial sliding surface of the second tongue portion.

[0141] As a result, the second leg portion provides two axial guiding surfaces. One of the axial guiding surfaces faces the recess of the frit, and the second axial guiding surface faces the second recess. The guiding surfaces are preferably arranged in parallel.

[0142] Preferably, the circumferential lengths of the first tongue portion and the second tongue portion are basically the same.

[0143] The locking end with only one tongue portion that can slide circumferentially in the corresponding recess can compensate for thermal expansion and wear of the liner. The above-mentioned locking section with only one tongue portion and the cross-linking section, and / or the above-mentioned groove and hole can further compensate for or withstand the radial force applied from the inside of the piston ring.

[0144] However, since the diameter of the piston ring is large compared to the cross-sectional dimensions, they cannot prevent the possible local twisting of the locking section. Specifically, the separate twisting movements of the male locking end and the female locking end cannot be suppressed. The locking section with overlapping locking ends that are twisted relative to each other may cause damage to the liner surface.

[0145] Since the male locking end has two tongue portions and the female locking end has two recesses formed in the same leg portion, the relative twisting of the locking ends is limited. The common leg portion enables the locking ends to be held in a row in the circumferential direction even when a torsional force is applied.

[0146] The first and second tongue portions and the first and second recesses are arranged parallel to each other in the circumferential direction. When both the first and second tongue portions are arranged on the piston, they have radially outer surfaces that face the outside of the piston ring and thus face the cylinder liner.

[0147] The same effect is also achieved by a piston ring having the first tongue portion and the first recess as described above and a second tongue portion having a radially outer surface facing the inside of the piston ring.

[0148] In this case, the male locking end also includes a second tongue portion, and the female locking end has a second recess such that the second tongue portion can be inserted into the second recess.

[0149] The second tongue portion has a maximum radial width narrower than the maximum width of the ring section and a maximum axial height lower than half of the height of the ring section.

[0150] The second tongue portion has a sliding surface facing radially outward over the circumferential length and the height of the second tongue portion. The second tongue portion has an axial sliding surface facing opposite to the axial sliding surface of the first tongue portion over the circumferential length and the radial width of the second tongue portion.

[0151] Correspondingly, the second recess is open towards the inside of the piston ring and is disposed between the third leg portion and the second leg portion.

[0152] The third leg portion has a radial width narrower than the width of the ring section and provides a guiding surface facing radially inward corresponding to the sliding surface facing outward of the second tongue portion.

[0153] The second leg portion provides a second axial guiding surface corresponding to the axial sliding surface of the second tongue portion.

[0154] In this case, the two recesses of the female locking end also include a common leg portion for preventing the twisting of the locking end. Further, since the first tongue portion has a sliding surface facing radially inward and the second tongue portion has a sliding surface facing radially outward, the relative radial movement of the locking end is restricted.

[0155] This problem is also solved by a piston of a reciprocating internal combustion engine provided with the above piston ring.

[0156] This problem is also solved by a reciprocating internal combustion engine, specifically, a large marine engine having at least one cylinder with an inner diameter of at least 200 mm, preferably a two-stroke engine and / or a two-stroke crosshead engine comprising the piston with the piston rings as described above.

[0157] This problem is also solved by the method for manufacturing a piston ring according to claim 12. The piston ring is preferably the piston ring as described above.

[0158] The method includes the following steps.

[0159] Prepare a raw material. The raw material can be prepared, for example, by casting from a cast iron material. The raw material can be formed as a closed ring having an essentially rectangular cross-section, or the raw material is prepared as a rod that will be bent into a ring later.

[0160] The locking section is milled or cut from the raw material. Thereby, a ring section having a male locking end and a female locking end is formed. The ring section has an axial height and a maximum radial width.

[0161] A tongue is formed at the male end of the piston ring, and a recess is formed at the female locking end such that the tongue can be inserted into the recess.

[0162] The tongue has a maximum radial width that is narrower than the maximum radial width of the ring section, and the tongue also has an axial height that is lower than the height of the ring section.

[0163] The tongue has a sliding surface facing radially inward over the circumferential length and the height of the tongue, and the tongue also has an axial sliding surface over the circumferential length and the radial width.

[0164] The recess is open towards the outside of the piston ring and is arranged between a first leg and a second leg.

[0165] The radial width of the first tibial part is narrower than the maximum width of the ring section. The first tibial part provides a guiding surface facing radially outwards that corresponds to the radial sliding surface of the tongue part.

[0166] The axial height of the second tibial part is lower than the height of the ring section. The second tibial part provides an axial guiding surface that corresponds to the axial sliding surface of the tongue part.

[0167] Preferably, the surface of the raw material, specifically the surface facing outwards of the raw material, is coated with a coating material, for example, chrome plating.

[0168] The method further includes the following steps.

[0169] Protrusions are provided on the circumferentially extending part of the guiding surface facing radially outwards of the first tibial part and / or on the circumferentially extending part of the sliding surface facing radially inwards of the tongue part.

[0170] Additionally or alternatively, depressions are provided on the guiding surface facing radially outwards of the first tibial part.

[0171] The protrusions and / or depressions are provided in such a way that the maximum width of the ring section is preferably 0.05 mm to 0.15 mm, or 0.1% to 0.6% of the maximum width of the ring section, narrower than the sum of the maximum width of at least the circumferentially extending part of the tongue part and the maximum width of at least the first circumferentially extending part of the first tibial part.

[0172] The piston can be mounted in the groove of the piston ring.

[0173] The overlapping part of the locking end part includes a crosslinked section.

[0174] Additionally or alternatively, the gas barrier can be provided on the tongue part, specifically on the circumferentially extending parts of the sliding surface facing radially inwards and the sliding surface facing axially of the tongue part.

[0175] In a preferred embodiment of the method, a protrusion is provided by coating, printing, adhesion, screwing, welding, soldering, flame spraying, laser processing, or electroplating on a portion of the guiding surface facing radially outward of the first shin portion and / or a portion of the sliding surface facing radially inward of the tongue portion, which portions extend in a first circumferential direction.

[0176] Preferably, a material having a hardness higher than that of the core of the piston ring is used to form the protrusion on the core of the piston ring.

[0177] Alternatively or additionally, the gas barrier may be provided by coating, printing, adhesion, screwing, welding, soldering, flame spraying, laser processing, or electroplating.

[0178] Preferably, a material having a hardness lower than that of the core of the piston ring is used to form the gas barrier on the core of the piston ring.

[0179] This problem is also solved by the method for manufacturing a piston ring according to claim 13. The piston ring is preferably the above-mentioned piston ring.

[0180] The method includes the following steps.

[0181] Prepare a raw material. The raw material can be prepared, for example, by casting from a cast iron material. The raw material can be formed as a closed ring having an essentially rectangular cross-section or as a rod that is bent into a ring.

[0182] The locking section is milled or cut from the raw material. Thereby, a ring section having a male locking end and a female locking end is formed. The ring section has an axial height and a maximum radial width.

[0183] A tongue is formed at the male end of the piston ring, and a recess is formed at the female locking end such that the tongue can be inserted into the recess.

[0184] The tongue has a maximum radial width that is narrower than the maximum width of the ring section, and the tongue also has an axial height that is lower than the height of the ring section.

[0185] The tongue has a sliding surface facing radially inward that extends over the circumferential length and the height of the tongue, and the tongue also has an axial sliding surface that extends over the circumferential length and the radial width.

[0186] The recess is open towards the outside of the piston ring and is arranged between the first leg portion and the second leg portion.

[0187] The radial width of the first leg portion is narrower than the maximum width of the ring section. The first leg portion provides a guiding surface facing radially outward that corresponds to the radial sliding surface of the tongue.

[0188] The axial height of the second leg portion is lower than the height of the ring section. The second leg portion provides an axial guiding surface that corresponds to the axial sliding surface of the tongue.

[0189] Preferably, the surface of the raw material, specifically the surface facing the outside of the raw material, is coated with a coating material, such as chrome plating.

[0190] The method further includes the following steps.

[0191] The groove and / or hole is cut, milled, or drilled in the male locking end portion and / or the female locking end portion. Specifically, at least one vertical groove is formed at the end of the male locking end portion.

[0192] Additionally or alternatively, at least one groove may be formed in the female locking end portion. The groove may be formed as an axially extending groove at the free end of the female locking end portion, specifically of the second leg portion, and / or as an axially extending groove within the recess, and / or as a circumferentially extending groove on the surface facing the outside of the second leg portion.

[0193] Additionally or alternatively, at least one hole, specifically an axial hole in the second shin, can be made in the female locking end.

[0194] This problem is also solved by a method for manufacturing a piston ring. The piston ring is preferably the above-mentioned piston ring.

[0195] The method includes the following steps.

[0196] Prepare a raw material. The raw material can be prepared, for example, by casting from a cast iron material. The raw material can be formed as a closed ring having an essentially rectangular cross-section or as a rod that is bent into a ring.

[0197] The locking section is milled or cut from the raw material. Thereby, a ring section with a male locking end and a female locking end is formed. The ring section has an axial height and a maximum radial width.

[0198] A tongue is formed at the male end of the piston ring, and a recess is formed at the female locking end such that the tongue can be inserted into the recess.

[0199] The tongue has a maximum radial width that is narrower than the maximum radial width of the ring section, and the tongue also has an axial height that is lower than the height of the ring section.

[0200] The tongue has a sliding surface facing radially inward over the circumferential length and the height of the tongue, and the tongue also has an axial sliding surface over the circumferential length and the radial width.

[0201] The recess is open towards the outside of the piston ring and is arranged between the first shin and the second shin.

[0202] The radial width of the first shin is narrower than the maximum radial width of the ring section. The first shin provides a guiding surface facing radially outward that corresponds to the radial sliding surface of the tongue.

[0203] The axial height of the second shin part is lower than the height of the ring section. The second shin part provides an axial guiding surface corresponding to the axial sliding surface of the tongue part.

[0204] Furthermore, the female end part can be formed to have a second recess, and the male end part can be formed to include a second tongue part, and as a result, the above piston ring is provided.

[0205] Further advantageous aspects of the present invention are described below using exemplary embodiments and figures. The following drawings are shown in a schematic form.

Brief Description of the Drawings

[0206]

Figure 1

Figure 2

Figure 3

Figure 4

Figure 5

Figure 6

Figure 7

Figure 8

Figure 9

Figure 10

Figure 11

Figure 12

Figure 13

Figure 14

Figure 15

Figure 16

Figure 17

Figure 18

Figure 19

DETAILED DESCRIPTION OF THE INVENTION

[0207] Elements having the same or similar functions are given the same reference numerals.

[0208] FIG. 1 shows a piston ring 100 for a piston of a reciprocating internal combustion engine in a perspective view.

[0209] The piston ring 100 includes a ring section 1 and a locking section 2 having a male locking end portion 3 and a female locking end portion 4.

[0210] The ring section 1 has a height 11 in the axial direction 201 and a maximum width 13 in the radial direction 202.

[0211] FIG. 2 shows a first example of the locking section 2 in a perspective view. The male locking end portion 3 includes a tongue portion 5, and the female locking end portion 4 has a recess 6 such that the tongue portion 5 can be inserted into the recess 6.

[0212] The tongue portion 5 has an axial height 36 that is lower than the height 11 of the ring section 1 (see FIG. 1).

[0213] The recess 6 is open toward the outside 44 of the piston ring 100 (see FIG. 1).

[0214] FIG. 3 shows the male locking end portion 3 of FIG. 2 in a perspective view. The tongue portion 5 of the male locking end portion 3 has a maximum radial width 15 that is narrower than the maximum width 13 of the ring section 1.

[0215] The tongue portion 5 basically has a sliding surface 34 facing radially inward that extends over the circumferential length 35 and the height 36 of the tongue portion 5. The tongue portion 5 further basically has an axial sliding surface 37 that extends over the circumferential length 35 and the radial width 15.

[0216] The free end 26 of the male locking end portion 3 is chamfered.

[0217] FIG. 4 shows, as compared with FIG. 1, an example of the locking section 2 in a top view from below.

[0218] The recess 6 of the female locking end portion 4 is disposed between the first shin portion 41 and the second shin portion 42.

[0219] The maximum width 13 of the ring section 1 is narrower than the sum of the maximum width 15 of at least the circumferentially extending portion 18 of the tongue portion 5 and the maximum width 16 of at least the first circumferentially extending portion 17 of the first shin portion 41.

[0220] The locking section 2 includes a bridging section 21, and the total maximum radial width 40 is still wider than the maximum width 13 of the ring section 1 even when the first shin portion 41 is pressed against the tongue portion 5.

[0221] FIG. 5 shows a cross-sectional view taken along line AA of FIG. 4, and thus shows an example of the locking section 2 along a plane extending in the axial direction 201 and the radial direction 202.

[0222] The recess 6 of the female locking end portion 4 is disposed between the first shin portion 41 and the second shin portion 42.

[0223] The first shin portion has a radial width 7 in the radial direction 202 that is narrower than the width 13 of the ring section 1 (see FIG. 1), and provides a guiding surface 9 facing radially outward that corresponds to the sliding surface 34 (see FIG. 3) facing inward of the tongue portion 5.

[0224] The second shin portion 42 has an axial height 10 in the axial direction 201 that is lower than the height 11 of the ring section 1, and provides an axial guiding surface 8 that corresponds to the axial sliding surface 37 (see FIG. 3) of the tongue portion 5.

[0225] The outward-facing surface 12 (see FIG. 1) of the piston ring 100 is warped, and in the region of the locking section 2, the maximum extension line 25 is disposed on the tongue portion 5.

[0226] Normally, the core of the piston ring 100 is formed such that the sum of the maximum radial width 116 of the tongue portion 5 and the maximum radial width 115 of the first leg portion 41 is narrower than the maximum radial width 13 (see FIG. 1) of the ring section 1.

[0227] In order to provide a crosslinking section 21 (see FIG. 4), a protrusion 20 is provided on the tongue portion 5.

[0228] When pressure is generated from the inside 46 of the locking section 2, the protrusion 20 ensures that the maximum extension line 25 remains in the outermost part of the locking section 2 and that the second leg portion 42 is not pushed radially outward from the tongue portion 5. Accordingly, the risk of damaging the liner by the edge 47 (see FIG. 2) that may protrude radially of the female locking end portion 4 is minimized.

[0229] The protrusion 20 can be provided by coating, printing, adhesion, screwing, welding, soldering, flame spraying, laser processing, or electroplating.

[0230] FIG. 6 shows an example of the locking section in another cross-sectional view in a plane perpendicular to the axial direction.

[0231] The recess 32 is disposed on the guiding surface 9 facing radially outward of the first leg portion 41. The recess 32 is disposed at a circumferential distance 45 from the free end portion 22 of the female locking end portion 4.

[0232] Then, adjacent to the recess 32, a crosslinking region 21 is formed where the sum of the maximum width 15 of the tongue portion 5 and the maximum width 16 of the first leg portion 41 is wider than the maximum width 13 (see FIG. 1) of the ring section 1.

[0233] The tongue portion 5 is provided with a protrusion 20 that substantially covers the entire sliding surface 34 (see FIG. 3) facing radially inward.

[0234] Alternatively, the protrusion may be arranged away from the free end 26 of the male locking end portion, and may cover only a part of the sliding surface 34 (not shown in the figure) facing radially inward.

[0235] Alternatively, the protrusion may be arranged on the guiding surface 9 facing radially outward of the first leg portion 41 (not shown in the figure), and may extend over a part of the circumferential length 23 of the first leg portion 41, that is, the circumferential length corresponding to the distance 45 (see FIG. 6), from the free end 22 of the female locking end portion 4. The protrusion may be arranged, for example, next to the recess 32 (not shown in the figure).

[0236] Due to the recess 32, the crosslinked region 21 is not arranged immediately adjacent to the free end 26 of the male locking end portion 3.

[0237] Therefore, when the pressing force is transmitted from the inside of the piston ring through the crosslinked section 21 to the tongue portion 5, the tongue portion is pressed against the liner. The free end 26 of the tongue portion 5 still has the freedom to bend inward, and as a result, the edge 48 of the tongue portion 5 does not damage the liner (not shown in the figure).

[0238] FIG. 7 shows a second example of the male locking end portion in a perspective view, and FIG. 8 shows a second example of the male locking end portion in a cross-sectional view taken along a plane perpendicular to the axial direction.

[0239] An axially extending groove 33 is arranged at the free end 26 of the tongue portion 5.

[0240] The groove 3 provides higher elasticity at the end of the tongue portion 5, so that the end of the tongue portion 5 can bend inward more easily when contacting the liner.

[0241] FIG. 9 shows a second example of the female locking end portion 4 in a perspective view. FIG. 10 shows a second example of the female locking end portion 4 in a cross-sectional view taken along a plane perpendicular to the axial direction.

[0242] The groove 27 extending in the axial direction is arranged at the free end 22 of the second shin part 42 of the female locking end part 3. Further, the axial hole 30 is arranged in the second shin part 42 of the female locking end part 4.

[0243] FIG. 11 shows a third example of the female locking end part 4 in a perspective view. FIG. 12 shows a third example of the female locking end part 4 in a cross-sectional view along a plane perpendicular to the axial direction.

[0244] The groove 29 extending in the circumferential direction is arranged on the outward-facing surface of the second shin part 42. The groove opens towards the free end 22 of the female locking end part 4.

[0245] FIG. 13 shows a fourth example of the female locking end part 4 in a perspective view. FIG. 14 shows a fourth example of the female locking end part 4 in a cross-sectional view along a plane perpendicular to the axial direction.

[0246] The groove 28 extending in the axial direction is arranged in the recess 6.

[0247] Not only the grooves 27, 28, 29 but also the holes 30 bring about higher elasticity and more appropriate dispersion of the mechanical load along the female locking end part 4, thereby avoiding high pressure peaks at the free end 22 of the female locking end part 4.

[0248] FIG. 15 shows a third example of the male locking end part 3 in a perspective view. The gas barrier 31 is arranged on the radially inward-facing sliding surface 34 and the axial sliding surface 37 of the tongue part 5.

[0249] The gas barrier 31 is arranged at a distance 49 from the free end 26 of the male locking end part 3.

[0250] FIG. 16 shows a third example of the locking section 2 in a perspective view. FIG. 17 shows a third example of the locking section 2 in a cross-sectional view along a plane extending in the axial direction 201 and the radial direction 202.

[0251] The male locking end portion 3 includes a first tongue portion 5 and a second tongue portion 5' that are parallel to the longitudinal direction of the tongue portion. Correspondingly, the female locking end portion 4 has a first recess 6 and a second recess 6', and both recesses open toward the outside 44 of the piston ring.

[0252] The first recess 6 is disposed between the first leg portion 41 and the second leg portion 42, while the second recess 6' is disposed between the third leg portion 43 and the second leg portion 42.

[0253] Since the male locking end portion 3 is circumferentially guided into the two recesses 6, 6', relative torsion of the locking end portions 3, 4 is prevented.

[0254] FIG. 18 shows a fourth example of the locking section 2 in a perspective view. FIG. 19 shows a fourth example of the locking section 2 in a cross-sectional view along a plane extending in the axial direction 201 and the radial direction 202.

[0255] The male locking end portion 3 includes a first tongue portion 5 and a second tongue portion 5'' that are parallel to the longitudinal direction of the tongue portion. Correspondingly, the female locking end portion 4 has a first recess 6 and a second recess 6'', the first recess 6 opens toward the outside 44 of the piston ring, and the second recess 6'' opens toward the opposite side.

[0256] The first recess 6 is disposed between the first leg portion 41 and the second leg portion 42, and the second recess 6' is disposed between the third leg portion 43' and the second leg portion 42.

[0257] Also, in this example, the two tongue portions 5, 5'' and the two recesses 6, 6'' prevent relative torsion of the locking end portions 3, 4.

[0258] Furthermore, since the recesses 6, 6'' do not open toward the same side, relative movement of the locking end portions 3, 4 in the radial direction 202 is prevented.

Claims

1. A piston ring (100) for a piston of a reciprocating internal combustion engine, wherein the piston ring (100) comprises: a ring section (1) and a locking section (2); The locking section comprises a male locking end (3) and a female locking end (4), and the ring section (1) has an axial height (11) in the axial direction (201) and a maximum width (13) in the radial direction (202); The male locking end (3) comprises a tongue (5), and the female locking end (4) has a recess (6), such that the tongue (5) can be inserted into the recess (6); The tongue (5) has a maximum radial width (15) that is narrower than the maximum width (13) of the ring section (1) and an axial height (36) that is lower than the height (11) of the ring section (1); The tongue (5) has a sliding surface (34) facing radially inward over the circumferential length (35) and the height (36) of the tongue (5), and the tongue (5) has an axial sliding surface (37) over the circumferential length (35) and the radial width (15); The recess (6) opens towards the outside (44) of the piston ring (100) and is arranged between a first leg (41) and a second leg (42); The first leg (41) has a radial width (7) that is narrower than the width (13) of the ring section (1) and provides a guiding surface (9) facing radially outward corresponding to the sliding surface (34) facing inward of the tongue (5); The second leg (42) has an axial height (10) that is lower than the height (11) of the ring section (1) and provides an axial guiding surface (8) corresponding to the axial sliding surface (37) of the tongue (5); The piston ring (100) is The piston ring (100) is characterized in that the maximum width (13) of the ring section (1) is narrower than the sum of the maximum width (15) of at least the circumferentially extending portion (18) of the tongue portion (5) and the maximum width (16) of at least the first circumferentially extending portion (17) of the first leg portion (41).

2. The piston ring (1) according to claim 1, wherein the outer-facing side surface (12) of the piston ring (100) is warped, and in the region of the locking section (2), the maximum extension line (25) is arranged on the tongue portion (5).

3. The piston ring (1) according to claim 1 or 2, wherein the first circumferentially extending portion (17) of the radially outward-facing guiding surface (9) of the first leg portion (41) is provided with a radially outward-facing protrusion.

4. The piston ring (1) according to claim 1 or 2, wherein the first circumferentially extending portion (18) of the radially inward-facing sliding surface (34) of the tongue portion (5) is provided with a radially inward-facing protrusion (20).

5. The piston ring (1) according to any one of claims 1 to 4, wherein the recess (32) is arranged on the radially outward-facing guiding surface (9) of the first leg portion (41).

6. - At least an axially extending groove (33) is arranged at the free end (26) of the male locking end portion (3), - At least one groove (27, 28, 29) is arranged at the female locking end portion (4), The piston ring (1) according to any one of claims 1 to 5, characterized by at least one of: at least one hole (30) is arranged at the female locking end portion (4).

7. The piston ring (100) according to any one of claims 1 to 6, wherein a gas barrier (31) is arranged at at least one of the locking end portions (3, 4). **Claim 8**: The male locking end portion (3) includes a second tongue portion (5'), and the female locking end portion (4) has a second recess (6'), such that the second tongue portion (5') can be inserted into the second recess (6'). The second tongue portion (5') has a maximum radial width (15') that is narrower than the maximum width (13) of the ring section (1), and an axial height (36') that is lower than half of the height (11) of the ring section (1). The second tongue portion (5') has a sliding surface (34') facing radially inward that extends over the circumferential length (35) and the height (36') of the second tongue portion (5'), and an axial sliding surface (37') that extends over the circumferential length (35') and the radial width (15') of the second tongue portion (5'). The second recess (6') opens towards the outside (44) of the piston ring (100) and is arranged between the third leg portion (43) and the second leg portion (42). The third leg portion (43) has a radial width (7) that is narrower than the width (13) of the ring section (1), and provides a guiding surface (9') facing radially outward that corresponds to the sliding surface (34') facing inward of the second tongue portion (5'). The second leg portion (42) provides a second axial sliding surface (8') that corresponds to the axial sliding surface (37') of the second tongue portion (5'). The piston ring (1) according to any one of claims 1 to 7, characterized in that. **Claim 9** A piston for a reciprocating internal combustion engine, comprising the piston ring (1) according to any one of claims 1 to 8. **Claim 10**: A reciprocating internal combustion engine for a large marine vessel having at least one cylinder with an inner diameter of at least 200 mm, which is a two-stroke engine and / or a two-stroke crosshead type engine, comprising the piston according to claim 9. A method for manufacturing a piston ring (100) according to any one of claims 1 to 8, comprising: - providing a raw material; - milling or cutting a locking end portion (2) from the raw material to thereby form a ring section (1), a male locking end portion (3), and a female locking end portion (4), wherein the ring section (1) has an axial height (11) and a maximum radial width (13), a tongue (5) is formed at the male end portion (3) of the piston ring (100), the tongue being insertable into a recess (5) of the female locking end portion (4), the tongue (5) has a maximum radial width (15) that is narrower than the maximum radial width (13) of the ring section (1), and an axial height (36) that is lower than the height (11) of the ring section (1), the tongue (5) has a sliding surface (34) facing radially inward over the circumferential length (35) and the height (36) of the tongue, and the tongue (5) has an axial sliding surface (37) over the circumferential length (35) and the radial width (15), the recess (6) is open towards the outside (44) of the piston ring (100) and is arranged between a first leg portion (41) and a second leg portion (42), the first leg portion (14) has a radial width (7) that is narrower than the maximum radial width (13) of the ring section (1), and provides a guiding surface (9) facing radially outward corresponding to the radial sliding surface (34) of the tongue, the second leg portion (42) has an axial height (10) that is lower than the height (11) of the ring section, and provides an axial guiding surface (8) corresponding to the axial sliding surface (37) of the tongue (5), - a step, and the method includes: - a first circumferentially extending portion (17) of the guiding surface (9) facing radially outward of the first leg portion (41), and / or The step of providing a protrusion (20) on a portion (18) of the sliding surface (34) facing radially inward of the tongue portion (5) and extending in a first circumferential direction ; and and - The step of providing a recess (32) in the guiding surface (9) facing radially outward of the first shin portion (41) further includes at least one of - As a result, the maximum width (13) of the ring section (1) is narrower than the sum of the maximum width (15) of at least the circumferentially extending portion (18) of the tongue portion (5) and the maximum width (16) of at least the first circumferentially extending portion (17) of the first shin portion (41). A method characterized by this.

12. The protrusion (20) of the portion (17) of the guiding surface (9) facing radially outward of the first shin portion (41) and extending in the first circumferential direction, and / or the portion (18) of the sliding surface (34) facing radially inward of the tongue portion (5) and extending in the first circumferential direction is provided by at least one of coating, printing, adhesion, screwing, welding, soldering, flame spraying, laser processing, and electroplating. The method according to claim 11.

13. A method for manufacturing a piston ring (1) according to any one of claims 1 to 7, comprising - The step of preparing a raw material - The step of milling or cutting a locking section (2) from the raw material to thereby form a ring section (1), a male locking end (3), and a female locking end (4), The ring section (1) has an axial height (11) and a maximum radial width (13), The tongue portion (5) is formed at the male end (3) of the piston ring (100), and the tongue portion can be inserted into the recess (5) of the female locking end (4), The tongue portion (5) has a maximum radial width (15) narrower than the maximum width (13) of the ring section (1) and an axial height (36) lower than the height (11) of the ring section (1), The tongue part (5) has a sliding surface (34) facing radially inward over the circumferential length (35) and the height (36) of the tongue part (5), and the tongue part (5) has an axial sliding surface (37) over the circumferential length (35) and the radial width (15). The recess (6) opens towards the outside (44) of the piston ring (100) and is arranged between the first leg part (41) and the second leg part (42). The first leg part (14) has a radial width (7) narrower than the maximum width (13) of the ring section (1), and provides a guiding surface (9) facing radially outward corresponding to the radial sliding surface (34) of the tongue part. The second leg part (42) has an axial height (10) lower than the height (11) of the ring section, and provides an axial guiding surface (8) corresponding to the axial sliding surface (37) of the tongue part (5). Steps and including, the method comprising: - a step of cutting, milling, or drilling a groove (27, 28, 29) and / or a hole (30) in the male locking end part (3) and / or the female locking end part (4), and - a step of providing at least one vertical groove (33) in the end part (26) of the male locking end part (3), - a step of providing at least one groove (27, 28, 29) in the female locking end part (4), and - a step of providing at least one hole (30) in the female locking end part (4) characterized by further including at least one of the above steps.

Images