DE102020101230B4 - Piston ring, piston machine with a piston ring and method for producing a piston ring - Google Patents

Abstract

Piston ring made of a fiber composite material with a matrix (12) and fibers (14) embedded therein, which piston ring (10) defines an axis (16) and an inner peripheral surface (32), an outer peripheral surface (34) spaced radially therefrom and an expansion opening (24) comprises, wherein the piston ring (10) can be expanded in the circumferential direction (18) of the axis (16) by enlarging the expansion opening (24), the fibers (14) on the piston ring (10) having different orientations in sections, the fibers (14) , at least on a deformation section (28) arranged at a distance from the expansion opening (24), along a thickness direction (20) of the piston ring (10) radially from the inner circumferential surface (32) to the outer circumferential surface (34), have different orientations, and wherein on at least one the The expansion opening (24) delimiting the end face (26) of the piston ring (10) is provided with at least one recess to form a labyrinth seal with a corresponding end face (26) of the piston ring (10).

Description

The present invention relates to a piston ring made of a fiber composite material with a matrix and fibers embedded therein.

The invention also relates to a piston engine with at least one such piston ring and a method for producing a piston ring.

The present disclosure further includes the use of at least one piston ring of the type mentioned above.

The WO 2018/234244 A1 describes different embodiments of piston rings, each consisting of a fiber composite material with a matrix and fibers embedded therein. These piston rings comprise a free carbon phase with a volume fraction of at least approximately 5%, whereby the respective piston ring itself has lubricating properties to support the lubricating properties of the engine. High mechanical stability, particularly due to the carbides, effectively prevents delamination of the piston ring. The piston ring has high temperature stability and is wear-resistant despite its lubricating properties.

In the WO 2018/234244 A1 Methods for producing different piston rings are also described.

Piston rings made of metallic ring structures are also known, which can be coated to increase wear resistance, for example with a so-called “diamond-like carbon” (DLC) coating. The disadvantage here is the brittle nature of the DLC layer, which makes it susceptible to damage resulting in the functional layer failing.

The DE 1 934 469 A describes a sealing ring with a fiber-reinforced composite body made of a plastic material.

The object of the present invention is to provide a piston ring made of a fiber composite material, which piston ring has improved functional properties.

This object is achieved according to the invention by a piston ring made of a fiber composite material with a matrix and fibers embedded therein, which piston ring defines an axis and comprises an inner circumferential surface, an outer circumferential surface spaced radially therefrom and an expansion opening, the piston ring being expandable in the circumferential direction of the axis while increasing the expansion opening is, wherein the fibers on the piston ring have different orientations in sections, wherein the fibers have different orientations, at least on a deformation section arranged at a distance from the expansion opening, along a thickness direction of the piston ring radially from the inner circumferential surface to the outer circumferential surface, and at least on one delimiting the expansion opening Front side of the piston ring has at least one recess to form a labyrinth seal with a corresponding front side of the piston ring.

The mechanical properties of the piston ring according to the present invention can be specifically influenced via the orientation of the fibers. For assembly, the piston ring must be expanded by increasing the expansion opening. The expansion opening can be limited in particular to end faces of the piston ring that face each other (“ring joint”), which are placed at a greater distance from one another. As a result of the expansion, the piston ring is subjected to mechanical stress, with the greatest stress occurring at the deformation section arranged at a distance from the expansion opening. According to the invention, different orientations of the fibers are provided at least at the deformation section, along the thickness direction from the inner peripheral surface to the outer peripheral surface. This gives the possibility in particular that the piston ring, at least on the deformation section, has different rigidities on the radial inside, radial outside and/or in between. On the one hand, this makes it possible to ensure sufficient deformability for improved assembly. On the other hand, it is possible to provide sufficiently good friction properties on the outer peripheral surface. Depending on the application and the quality to be achieved, the piston ring can be provided with suitable rigidity.

It is understood that in the present case the orientations of the fibers in the reference system of the piston ring are considered, so to speak in the form of cylindrical coordinates with an axial direction, a circumferential direction around the axis and a radial direction with respect to the axis.

It may be preferred in particular if the deformation section is diametrically opposite the expansion opening in particular with respect to the axis.

Alternatively, it can be provided that the deformation section has an angular distance from the expansion opening with respect to the axis that is less than 180°.

The deformation section can, for example, have an angular range of cover at least about 10°, preferably at least about 20° and above.

More than just one deformation section can be provided.

It can be provided that an angle of the orientation of the fibers with respect to the axial direction is larger adjacent to the inner peripheral surface than adjacent to the outer peripheral surface.

Alternatively, it can be provided that an angle of the orientation of the fibers with respect to the axial direction adjacent to the inner peripheral surface is smaller than on the outer peripheral surface.

Alternatively, it can be provided that an angle of the orientation of the fibers with respect to the axial direction adjacent to the inner circumferential surface is the same size or substantially the same size as on the outer circumferential surface.

• - ungefähr 10° bis 80°, vorzugsweise ungefähr 20° bis 70°, bevorzugt ungefähr 30° bis 60°, beispielsweise ungefähr 45°;
• - weniger als ungefähr 10° bis ungefähr 0°;
• - mehr als ungefähr 80° bis ungefähr 90°.

For example, it can be provided that an orientation of the fibers adjacent to the inner circumferential surface includes an angle with the axial direction, which is one of the following:

• - about 10° to 80°, preferably about 20° to 70°, preferably about 30° to 60°, for example about 45°;
• - less than about 10° to about 0°;
• - more than about 80° to about 90°.

• - ungefähr 10° bis 80°, vorzugsweise ungefähr 20° bis 70°, bevorzugt ungefähr 30° bis 60°, beispielsweise ungefähr 45°;
• - weniger als ungefähr 10° bis ungefähr 0°;
• - mehr als ungefähr 80° bis ungefähr 90°.

Alternatively or additionally, it can be provided that an orientation of the fibers adjacent to the outer peripheral surface includes an angle with the axial direction, which is one of the following:

• - about 10° to 80°, preferably about 20° to 70°, preferably about 30° to 60°, for example about 45°;
• - less than about 10° to about 0°;
• - more than about 80° to about 90°.

The stiffness of the piston ring can be varied by the angle of the fibers with respect to the axial direction. Accordingly, it can be provided that when producing the piston ring, the fibers are arranged with different orientation along the thickness direction at least on the deformation section. The manufacturing processes will be discussed in detail below.

For now, however, it can be mentioned, for example, that the fibers can be applied to a core, for example by means of a winding process. It can be advantageous here if the fibers have a minimum angle on the radial inside and/or radial outside with respect to the axial direction, which is greater than 0°, due to the winding method used. In a corresponding manner, it can be provided that, due to the winding method used, an angle of the fiber orientation is not aligned exactly perpendicular to the axial direction, but is slightly different from 90 ° in order to simplify the winding process.

It can be provided that fibers of different properties are used along the thickness direction, at least on the deformation section. For example, the fibers differ from each other in terms of their thickness and/or tensile strength.

Alternatively or additionally, it can be provided that different densities of the fibers are arranged along the thickness direction, at least on the deformation section.

Practical investigations show that a crack in the piston ring can occur more frequently on the inner circumferential surface than on the outer circumferential surface. Therefore, a lower rigidity of the piston ring on the inner peripheral surface than on the outer peripheral surface may be preferred.

With regard to advantageous friction properties, practice shows that a high rigidity of the piston ring on the outer peripheral surface can be advantageous.

Therefore, it may be advantageous if the rigidity of the piston ring, at least at the deformation section, is higher adjacent to the outer peripheral surface than adjacent to the inner peripheral surface, or that the rigidity adjacent to the inner peripheral surface is higher than adjacent to the outer peripheral surface.

In a different advantageous embodiment of the piston ring according to the invention, it can be provided that the rigidity of the piston ring, at least at the deformation section, adjacent to the inner peripheral surface is the same or essentially the same as adjacent to the outer peripheral surface, and / or in each case larger or smaller than in a radial intermediate area of the piston ring. This can, for example, open up the possibility of counteracting crack formation on the inner circumferential surface and at the same time achieving advantageous friction properties on the outer circumferential surface.

In a different advantageous embodiment of the piston ring according to the invention It can be advantageous if the rigidity of the piston ring, at least at the deformation section, adjacent to the inner circumferential surface, adjacent to the outer circumferential surface and radially in between are different from one another.

It can be provided that the orientations of the fibers, along the thickness direction, differ from one another in the entire circumferential direction, in particular to form different stiffness of the piston ring. This can, for example, simplify the production of the piston ring, for example by means of a winding or braiding process.

It may be advantageous if the piston ring has two or more adjacent or merging layers along the thickness direction, the orientations of the fibers within a respective layer being identical or substantially identical, preferably along the entire circumferential direction. Within a layer, the orientations of the fibers are at least essentially the same, although the orientations of the fibers in different layers differ from one another.

The two or more layers can, for example, be provided in a simple manufacturing manner by means of a winding process, braiding process, or by positioning woven fibers or nonwoven fabric in different webs.

It can be provided that the two or more layers have the same or essentially the same layer thicknesses. Alternatively, it can be provided that at least two layers have the same or essentially the same layer thicknesses and/or that at least two layers have different layer thicknesses.

It can be provided that within a respective layer there is only one orientation of the fibers or two or more orientations, in particular two orientations in the case of a fiber fabric or a fiber braid. For example, a first layer with two orientations oriented at an angle to one another, formed by a fabric or a braid, of fibers is provided. In a further layer, the fibers can have at least one different orientation. Here, for example, two different orientations aligned at an angle to one another can be provided, again formed by means of a braid or a fabric.

A respective orientation of the fibers within a layer can be a preferred direction of fibers, for example when producing the piston ring using fiber fleece. The fiber fleece provided in webs can, for example, have a respective preferred direction in two or three dimensions, although deviations from this preferred direction can arise within the web.

Alternatively, it can be provided that the respective orientation is identical for all fibers within a layer.

In a preferred embodiment of the piston ring according to the invention, it can be provided that the orientations of the fibers vary continuously along the thickness direction. For example, fiber orientations can be continuously changed radially from the inside to the outside in layers lying one above the other using a winding or braiding process.

It can prove to be particularly advantageous if the fibers are each aligned in a lateral surface around the axis. This can be understood in particular to mean that the orientations have no or essentially no radial component. In particular, however, an axial component and/or a component in the circumferential direction can be provided.

The fibers can be, for example, wound fibers.

The fibers can, for example, form a fiber mesh or a fiber fabric.

The fibers are arranged, for example, in layers radially one above the other with a respective orientation. As already mentioned, this can be achieved, for example, by providing a fiber fleece, for example a wet fleece, in strips. The sheets can be placed on top of each other in different layers with different preferred directions. When using fiber fleece for production, it can be, for example, a parallel fleece in which the fibers are longitudinally oriented or in which the fibers are transversely oriented. Alternatively, a cross-layer nonwoven with longitudinally or transversely oriented fibers that have at least two preferred directions can be used. The mechanical structural properties of nonwoven semi-finished products such as strength, force-strain behavior, elasticity and/or flexural rigidity can be influenced more or less along at least one preferred direction depending on the manufacturing process by aligning the fibers. For parallel nonwovens with a manufacturing direction “MD” (machine direction), a preferred orientation MD:CD of, for example, approximately 5:1 to 14:1 can be achieved, where “CD” indicates the cross direction transverse to the machine direction. With cross-layer fleece can a strength MD:CD, for example, up to approx. 1:1 can be achieved.

It can be provided in particular that the matrix comprises carbide and a free carbon phase and/or that the fiber composite material is C/C-SiC.

The nature of the fiber composite material can in particular be as in the WO 2018/234244 A1 the same applicant is described. The content and disclosure of this publication are incorporated in their entirety into this disclosure.

The fiber composite material preferably comprises fibers and a matrix, wherein the matrix can be formed from a carbon precursor (carbon-containing resin or the like) in which the fibers are embedded. The fibers can be pre-impregnated with the carbon precursor (pre-preg) or infiltrated (subsequently impregnated). The carbon precursor with the fibers can be hardened, for example by pressing and/or heating. Through subsequent pyrolysis, the precursor can be carbonized and a porous near-net-shape body with a carbon-containing matrix can be formed, into which a carbide former can be introduced. The carbide former reacts with the carbon of the porous body to form carbide. Carbide regions can be formed around carbon portions of the matrix.

There is preferably the possibility of specifically influencing the properties of the piston ring through the formation of carbide; in particular, the free carbon phase can be influenced. The selection of the carbide former and the selection of the fiber material also make it possible to influence the mechanical stability, heat conduction and/or thermal expansion of the piston ring.

Different preferred carbide formers can be used. For example, silicon carbide, tungsten carbide or titanium carbide have proven to be advantageous.

It can be provided that the free carbon phase comprises a proportion of more than 5% by volume. This improves the lubricating properties of the piston ring.

For example, the free carbon phase can have a proportion of approximately 5% by volume to approximately 25% by volume, in a preferred embodiment preferably approximately 10% by volume to approximately 20% by volume.

• - Kohlenstofffasern;
• - metallische Fasern, beispielsweise Wolframfasern oder Molybdänfasern, oder Fasern aus oder basierend auf einer Metalllegierung, beispielsweise einer Wolframlegierung oder einer Molybdänlegierung;
• - oxidische Fasern, beispielsweise aus Aluminiumoxid oder Zirkonoxid;
• - Fasern aus einem Carbidmaterial, beispielsweise aus Siliziumcarbid.

The fiber composite material is highly mechanically resilient due to the fibers embedded in the matrix. The fibers are or include, for example, one of the following:

• - carbon fibers;
• - metallic fibers, for example tungsten fibers or molybdenum fibers, or fibers made of or based on a metal alloy, for example a tungsten alloy or a molybdenum alloy;
• - Oxidic fibers, for example made of aluminum oxide or zirconium oxide;
• - Fibers made of a carbide material, for example silicon carbide.

In an advantageous embodiment of the piston ring according to the invention, the fiber composite material is C/C-SiC. To form it, for example, carbon fibers are pre-impregnated or infiltrated with a carbon precursor and shaped. The fiber matrix material is cured. In the present case, “hardening” can be viewed in particular as hardening by pressing and/or exposure to temperature, including pyrolysis, to form a porous body with a carbon-containing matrix. By siliconizing with liquid silicon, silicon carbide is formed, which forms areas around the free carbon components to increase the mechanical strength.

The piston ring can be formed in one piece or in several pieces.

The piston ring can have ring joints of different properties at the expansion opening. This will be discussed further below.

It can be advantageous if the piston ring has at least one groove on the outer peripheral surface that runs at least partially in the circumferential direction to form a labyrinth seal with a piston receptacle.

Additionally or alternatively, at least one oil scraper groove can be provided on the outer peripheral surface.

At least one recess for forming a labyrinth seal with a corresponding end face of the piston ring is provided on at least one end face of the piston ring delimiting the expansion opening. This labyrinth seal can be used to reduce the so-called “blow-by” in the area of the ring joint.

As mentioned at the beginning, the present invention also relates to a piston engine. The piston engine according to the present invention has at least one piston which can be moved back and forth in a piston receptacle and on which at least one piston ring of the type mentioned above is arranged.

An advantageous embodiment of the piston engine can be an engine or include an engine, in particular a free-piston engine. The piston of the engine can in particular be a combustion piston.

In a different advantageous embodiment, the piston engine is or comprises a compressor.

The present disclosure also relates to use. A piston ring of the type mentioned above is used in a piston engine, for example an engine, in particular a free-piston engine of a free-piston device.

• - Anordnen von Fasern zur Bildung eines Körpers in Form eines insbesondere senkrechten, eine Achse definierenden Kreiszylinders derart, dass radial bezüglich der Achse zumindest zwei Lagen von Fasern angeordnet werden und die Fasern in Umfangsrichtung der Achse über einen vorgegebenen oder vorgebbaren Winkelbereich entlang einer Radialrichtung unterschiedliche Orientierungen aufweisen;
• - Bereitstellen und Aushärten einer Matrix für die Fasern.
• - Ausbilden von mindestens einer Ausnehmung an zumindest einer die Aufweitöffnung begrenzenden Stirnseite des Kolbenrings zur Ausbildung einer Labyrinthdichtung mit einer korrespondierenden Stirnseite des Kolbenrings.

A method according to the invention for producing a piston ring according to the invention comprises the following steps:

• - Arranging fibers to form a body in the form of a particularly vertical circular cylinder defining an axis in such a way that at least two layers of fibers are arranged radially with respect to the axis and the fibers have different orientations in the circumferential direction of the axis over a predetermined or predeterminable angular range along a radial direction exhibit;
• - Providing and curing a matrix for the fibers.
• - Forming at least one recess on at least one end face of the piston ring delimiting the expansion opening to form a labyrinth seal with a corresponding end face of the piston ring.

The advantages that have already been mentioned in connection with the explanation of the piston ring according to the invention can also be achieved using the method as well as in the piston engine and using the use. In this regard, reference can be made to the above statements. Advantageous embodiments of the method according to the invention, the piston machine according to the invention and the use according to the invention result from advantageous embodiments of the piston ring according to the invention. In this regard, reference can also be made to the above statements.

In the method according to the invention, the fibers are arranged to form a body. This can be a body close to the final shape for forming the piston ring itself. Alternatively, for example, an elongated cylindrical body can be formed, which is axially divided into individual segments to form respective piston rings, as explained below.

At least two layers have fibers with different orientations - at least over a predetermined or predeterminable angular range that corresponds to the later deformation section.

The fibers of the body are embedded in a matrix in the piston ring according to the invention. In the process, the matrix is provided and hardened, whereby the body can be hardened and prepared for any further process steps.

Arranging the fibers can be accomplished, for example, by winding the fibers onto a core, changing the fiber orientation through an angle at which the fibers are wound on the core.

Arranging the fibers can be accomplished, for example, by braiding the fibers onto a core, changing the fiber orientation via an angle at which the fibers are braided onto the core. A respective braid has in particular two fiber directions arranged crosswise to one another.

The fibers can be arranged, for example, by providing two or more layers of fiber fabric, in particular cross-woven. The layers can be placed on the core, with layers on top of each other being placed on the core at different angles.

The fibers can be arranged, for example, by providing two or more layers of fiber felt, which have a respective preferred orientation of the fibers contained therein. This can, for example, be the parallel fleece mentioned above, longitudinally or transversely oriented, or the cross-layer fleece, longitudinally and transversely oriented.

Arranging the fibers can be done, for example, by 3D printing matrix material containing fibers.

The fibers can be arranged, for example, by arranging and specifically positioning individual fibers on a core using “tailored fiber placement” (TFP).

The fibers can be arranged, for example, by providing and positioning fiber strands on the core using a pultrusion device.

The fibers can be arranged, for example, by providing them using an injection molding process, with the fibers being embedded in matrix material.

In the method it can be provided that the fibers are provided pre-impregnated with matrix material (prepreg) during the arranging step. Alternatively, it can be provided that the fibers are infiltrated with a matrix material after they have been arranged.

It can be provided that the body is divided axially into a plurality of rings after the matrix material has hardened. Alternatively, the body already has the shape of the piston ring that is close to the final shape or has the same shape as the final shape.

For example, after hardening or when arranging the fiber, an expansion opening and accordingly a ring joint can be formed on the body.

The body or the piston ring can, for example, be reworked. In particular, reworking can be carried out by grinding, in particular the outer peripheral surface. Further post-processing options include, for example, introducing at least one groove on the outer peripheral surface and/or introducing at least one recess on an end face delimiting the expansion opening.

To the one already referenced WO 2018/234244 A1 is referred to again with regard to the introduction of a carbide former into a carbon-containing matrix. The steps described in this publication for carbidizing and providing a free carbon phase of the piston ring can also be used here in preferred embodiments of the method according to the invention.

• 1: eine perspektivische schematische Darstellung eines erfindungsgemäßen Kolbenrings;
• 2: den Kolbenring in Draufsicht axial in einem unaufgeweiteten Zustand;
• 3: eine Darstellung entsprechend 2, wobei der Kolbenring aufgeweitet ist;
• 4A bis 4C: schematische Darstellungen von radial übereinander angeordneten Schichten des Kolbenrings aus 1, wobei diese in der Zeichnung übereinander dargestellt sind und Orientierungen der Fasern des Kolbenrings schematisch gezeigt sind, wobei die Schichten durch Ausbreiten der Mantelfläche in einer Ebene gezeigt sind;
• 5: eine vergrößerte Detaildarstellung von Detail A in 4;
• 6A bis 6C: eine Darstellung entsprechend den 4A bis 4C bei einem andersartigen erfindungsgemäßen Kolbenring in einer Detailansicht;
• 7: eine schematische vergrößerte Darstellung von Detail B in 6A;
• 8A bis 8C: eine Darstellung entsprechend den 4A bis 4C bei einem andersartigen erfindungsgemäßen Kolbenring in einer Detailansicht;
• 9A bis 9C: eine Darstellung entsprechend den 4A bis 4C bei einem andersartigen erfindungsgemäßen Kolbenring in einer Detailansicht;
• 10A bis 10C: eine Darstellung entsprechend den 4A bis 4C bei einem andersartigen erfindungsgemäßen Kolbenring in einer Detailansicht;
• 11A bis 11C: eine Darstellung entsprechend den 4A bis 4C bei einem andersartigen erfindungsgemäßen Kolbenring in einer Detailansicht;
• 12A bis 12C: eine Darstellung entsprechend den 4A bis 4C bei einem andersartigen erfindungsgemäßen Kolbenring in einer Detailansicht;
• 13A bis 13C: eine Darstellung entsprechend den 4A bis 4C bei einem andersartigen erfindungsgemäßen Kolbenring in einer Detailansicht;
• 14A und 14B: schematische Darstellungen von zwei radial übereinander angeordneten Schichten des Kolbenrings aus 1, wobei diese in der Zeichnung übereinander dargestellt sind und Orientierungen der Fasern des Kolbenrings schematisch gezeigt sind, wobei die Schichten durch Ausbreiten der Mantelfläche in einer Ebene gezeigt sind;
• 15 und 15B: eine Darstellung entsprechend den 14A bis 14C bei einem andersartigen erfindungsgemäßen Kolbenring in einer Detailansicht;
• 16 bis 27: beispielhafte Darstellungen für unterschiedliche Ausführungsformen von Ringstößen eines erfindungsgemäßen Kolbenrings, wobei in den 16 bis 23 und 27 jeweils oben eine Seitenansicht des Kolbenrings und jeweils unten eine Draufsicht auf den Kolbenring in axialer Richtung gezeigt ist;
• 28 bis 30: schematische vergrößerte Darstellungen einer Außenumfangsfläche eines erfindungsgemäßen Kolbenrings angrenzend an eine Kolbenaufnahme;
• 31: eine schematische vergrößerte Darstellung eines Ringstoßes mit einer Aufweitöffnung eines erfindungsgemäßen Kolbenrings;
• 32: eine Schnittansicht einer Freikolbenvorrichtung in einer Teildarstellung, wobei die Freikolbenvorrichtung eine als Freikolbenmotor ausgebildete erfindungsgemäße Kolbenmaschine umfasst;
• 33: eine Darstellung zur Illustration des erfindungsgemäßen Verfahrens, bei dem Fasern auf einen Kern gewickelt werden;
• 34: eine Darstellung entsprechend 33, bei der Fasern auf einen Kern geflochten werden;
• 35: schematisch die Anordnung übereinanderliegender Lagen mit Fasern auf einem Kern;
• 36: eine schematische Detaildarstellung eines längsorientierten Parallelvlieses mit Fasern;
• 37: eine schematische Darstellung eines querorientierten Parallelvlieses mit Fasern; und
• 38: eine schematische Darstellung eines längs und quer orientierten Kreuzlagenvlieses mit Fasern.

The following description of preferred embodiments of the invention serves to explain the invention in more detail in conjunction with the drawing. Show it:

• 1 : a perspective schematic representation of a piston ring according to the invention;
• 2 : the piston ring in plan view axially in an unexpanded state;
• 3 : a representation accordingly 2 , with the piston ring expanded;
• 4A until 4C : Schematic representations of layers of the piston ring arranged radially one above the other 1 , whereby these are shown one above the other in the drawing and orientations of the fibers of the piston ring are shown schematically, the layers being shown by spreading the lateral surface in one plane;
• 5 : an enlarged detail view of detail A in 4 ;
• 6A until 6C : a representation corresponding to the 4A until 4C a detailed view of a different type of piston ring according to the invention;
• 7 : a schematic enlarged representation of detail B in 6A ;
• 8A until 8C : a representation corresponding to the 4A until 4C a detailed view of a different type of piston ring according to the invention;
• 9A until 9C : a representation corresponding to the 4A until 4C a detailed view of a different type of piston ring according to the invention;
• 10A until 10C : a representation corresponding to the 4A until 4C a detailed view of a different type of piston ring according to the invention;
• 11A until 11C : a representation corresponding to the 4A until 4C a detailed view of a different type of piston ring according to the invention;
• 12A until 12C : a representation corresponding to the 4A until 4C a detailed view of a different type of piston ring according to the invention;
• 13A until 13C : a representation corresponding to the 4A until 4C a detailed view of a different type of piston ring according to the invention;
• 14A and 14B : Schematic representations of two layers of the piston ring arranged radially one above the other 1 , whereby these are shown one above the other in the drawing and orientations of the fibers of the piston ring are shown schematically, the layers being shown by spreading the lateral surface in one plane;
• 15 and 15B : a representation corresponding to the 14A until 14C a detailed view of a different type of piston ring according to the invention;
• 16 until 27 : exemplary representations for different embodiments of ring joints of a piston ring according to the invention, in which 16 until 23 and 27 a side view of the piston ring is shown at the top and a top view of the piston ring in the axial direction is shown at the bottom;
• 28 until 30 : schematic enlarged representations of an outer peripheral surface of a piston ring according to the invention adjacent to a piston receptacle;
• 31 : a schematic enlarged representation of a ring joint with an expansion opening of a piston ring according to the invention;
• 32 : a sectional view of a free-piston device in a partial representation, the free-piston device comprising a piston engine according to the invention designed as a free-piston engine;
• 33 : a representation to illustrate the method according to the invention, in which fibers are wound on a core;
• 34 : a representation accordingly 33 , in which fibers are braided onto a core;
• 35 : schematically the arrangement of superimposed layers with fibers on a core;
• 36 : a schematic detailed representation of a longitudinally oriented parallel fleece with fibers;
• 37 : a schematic representation of a transversely oriented parallel fleece with fibers; and
• 38 : a schematic representation of a longitudinally and transversely oriented cross-layer fleece with fibers.

The 1 until 3 show schematic representations of a piston ring according to the invention, designated overall by reference number 10, in a preferred embodiment. The piston ring 10 is made of a fiber composite material that includes a matrix 12 and fibers 14 embedded therein. The fiber composite material is preferably C/C-SiC and preferably has a free carbon phase of, for example, at least 5%. The nature of the fiber composite material and its production have already been discussed above with reference to WO 2018/234244 A1 received.

Like in particular from the 2 and 3 As can be seen, the piston ring 10 defines an axis 16. A circumferential direction with respect to the axis 16 is identified by the reference numeral 18. A radial direction with respect to the axis 16, which radial direction is a thickness direction of the piston ring 10, is identified by the reference numeral 20.

In an exemplary implementation in practice when used in internal combustion engines of motor vehicles, the piston ring 10 has, for example, a diameter of less than 100 mm. For example, around 80 mm is common. A height of the piston ring 10 in the axial direction can be, for example, less than approximately 5 mm, with approximately 1 mm being common. A thickness of the piston ring 10 in the radial direction 20 can be, for example, less than approximately 5 mm, with approximately 3 mm being common, for example.

It is understood that the dimensions of the piston ring according to the invention can deviate from the above-mentioned values, for example when used in ship engines or compressors.

Like in particular from the 2 and 3 As can be seen, the piston ring 10 comprises an annular joint 22 with an expansion opening 24 which is limited to opposite end faces 26 of the piston ring 10.

For assembly, the piston ring 10 can be expanded by enlarging the expansion opening 24. This is in 3 shown.

When expanding, the piston ring 10 is particularly stressed at a deformation section 28. In the present example, the deformation section of the expansion opening 24 lies opposite the axis 16.

An angular range 30 of the deformation section 28 can be, for example, approximately more than 10°, approximately more than 20° and above.

However, stresses due to the deformation can occur on the piston ring 10 in particular along the entire circumference.

According to the present invention it is provided that the fibers 14 of the piston ring 10 have different orientations. There is a variation of the orientations at least on the deformation section 28 along the thickness direction 20 from an inner circumferential surface 32 to an outer circumferential surface 34 of the piston ring 10.

By varying the orientations of the fibers 14, the piston ring 10, in particular at the deformation section 28, can be provided with such rigidity that, on the one hand, easier assembly is possible and, on the other hand, sufficient stability is ensured in which crack formation can be avoided.

In addition, by providing the orientations of the fibers that differ from each other along the thickness direction 20 at least at the deformation section 28, in particular at the outer peripheral surface 34 for each Application provides the best possible friction properties with sufficient wear resistance.

It is advantageous if the rigidity of the piston ring 10 is constant along the entire circumferential direction 18, and not just at the deformation section 28.

In order to achieve different stiffnesses due to different orientations of the fibers in the thickness direction 20, it is preferably provided that the piston ring 10 has layers lying radially one above the other. The ones in the 1 until 4C For example, the embodiment shown has three layers 36, 38 and 40 radially from the inside to the outside.

It can be provided that the piston ring 10 according to the invention only has two layers. On the other hand, it can be provided that more than three layers are provided.

Within a respective layer, the fibers 14 preferably have an identical or substantially identical orientation, with the orientations of the fibers 14 of at least two layers differing from one another.

In the drawing, the fibers 14 in the respective layers are only partially shown so that they and the orientations can be better recognized. Areas free of fibers 14 and/or the distances between the fibers 14 shown in the drawing, the density of the fibers 14 and the docking of the fibers 14 are therefore not representative. Depending on requirements, the piston ring 10 can have areas free of fibers 14.

The fibers 14 preferably have an identical or substantially identical orientation along the entire circumferential direction 18, not just at the deformation section 28. As explained above, the orientations of the fibers 14 are viewed in the reference system of the piston ring 10, so to speak in cylindrical coordinates. Accordingly, the orientations may have an axial component along the axis 16, a component in the circumferential direction 18 and/or a component in the radial direction 20.

It can be particularly advantageous if the orientations of the fibers 14 run within only the respective layers in a lateral surface around the axis 16 and in particular no radial component is provided in the radial direction 20.

In a preferred embodiment of the piston ring according to the invention, it can be provided that the orientations of the fibers 14 vary continuously in the thickness direction 20, at least at the deformation section 28, deviating from the layer-by-layer variation of the orientations of the fibers 14 discussed below.

Below, with reference to the groups of figures 4, 6, 8, 9, 10, 11, 12, 13, 14 and 15, reference is made to exemplary orientations of fibers 14 depending on the respective layer. In groups of figures 4, 6, 8 to 13, the three layers 36, 38 and 40 are provided by way of example and in a non-restrictive manner for the present invention. In the embodiments of the groups of figures 14 and 15, only a radially inner layer 36 and a radially outer layer 40 are provided.

In the groups of figures mentioned above, an arrow 42 indicates the axial direction and an arrow 44 indicates the circumferential direction. The radially inner layer 36 is shown above, the radially outer layer 40 is shown below.

The 4A until 4C show that the layer 36 has fibers 14 with a substantially axial orientation. The middle layer 38 has fibers 14 that are inclined at an angle of approximately 45° with respect to the axial direction. The same applies to the layer 40, although the inclination of the fibers 14 is opposite to the inclination of the fibers 14 in the layer 38 with respect to the axial direction.

With such an orientation of fibers 14, the piston ring 10 can, for example, be made less rigid radially on the inside and relatively stiffer radially in the middle and on the outside.

5 shows an enlarged detailed view of 4A . It can be seen that the orientation of the fibers 14 preferably forms an angle 46 with respect to the axial direction, which is different from 0°. This simplifies the production of the piston ring 10, in particular by means of a winding process. The angle 46 may be, for example, approximately -5° to 5° to approximately -10° to 10°.

The same applies to the following embodiments, in which a course of the fibers 14 in the axial direction is shown in the drawing to simplify the explanation.

In the embodiment according to 6A , 6B and 6C the fibers 14 in the layer 36 are aligned radially on the inside approximately in the circumferential direction 18. In layer 38 in the middle, the fibers 14 are at approximately 45° aligned inclined with respect to the axis 16 (and with respect to the circumferential direction 18). In the layer 40, on the radial outside, the fibers 14 are aligned approximately in the axial direction.

7 shows an enlarged view according to 6A . It is shown how an angle 48 can exist between the orientation of the fibers 14 and the circumferential direction 18. For example, angle 48 is approximately -5° to 5° to approximately -10° to 10°. Corresponding to the above embodiments in relation to 5 For example, winding the fibers 14 proves to be advantageous if they do not run exactly along the circumferential direction 18, but are inclined at an angle 48 relative to it. The same applies to the following explanations with regard to the further embodiments, in which the orientation of the fibers 14 along the circumferential direction 18 are shown to simplify the explanations.

In the variant according to 6A until 6C High rigidity can be achieved in layer 36, lower rigidity in the middle and even lower rigidity in layer 40.

In the embodiments according to 8A until 8C the fibers 14 in the layer 36 are inclined radially on the inside by approximately 45 ° with respect to the axis 16. In the middle layer 38, the fibers 14 are inclined at a smaller angle with respect to the axis 16, for example approximately 25°. In layer 40, the fibers 14 are approximately aligned in the axial direction.

In the variant according to 9A until 9C The same applies to the orientation in layers 36 and 38. In the layer 40, on the radial outside, the fibers 14 are aligned approximately along the circumferential direction 18.

In the variant according to the group of figures 8, the piston ring 10 has a stiffness that decreases from the inner circumferential surface 32 to the outer circumferential surface 34. In the variant according to the group of figures 9, the piston ring 10 has a lower rigidity in the middle (layer 38) compared to the layer 36. The stiffness is highest in layer 40 on the radial outside.

The variants according to groups of figures 10 and 11 are designed in exactly the opposite way with regard to the orientation of the fibers 14 as the variants according to groups of figures 8 and 9, respectively.

In the variant according to 10A The fibers 14 are approximately axially aligned in layer 36, inclined relative to axis 16 in layer 38 (e.g., approximately 25°), and inclined at approximately 45° relative to axis 16 in layer 40.

The variant according to the 11A until 11C differs from the latter variant in that in the layer 36 the fibers 14 have an orientation approximately in the circumferential direction 18.

In the variant according to the group of figures 10, the piston ring 10 has a stiffness that increases from the inner peripheral surface 32 to the outer peripheral surface 34. In the variant according to the group of figures 11, the piston ring 10 has a lower rigidity in the middle (layer 38) compared to the layer 40. The stiffness is highest in layer 36 on the radial inside.

While the fibers 14 explained so far with reference to the groups of figures 4, 6 and 8 to 11 only have one orientation within each layer and are produced, for example, by winding, the variants of the groups of figures 12 and 13 now explained have fibers 14 with two different ones within each layer orientations. The fibers 14 are produced, for example, by a braid or a fabric.

The variant of 12A until 12C has in the layer 36 a fabric or braid 50 with fibers 14 whose orientations run approximately in the axial direction and approximately in the circumferential direction. In the layer 38, the respective orientations are inclined relative to the axis 16 or the circumferential direction 18, for example by approximately 25°. In layer 40, the respective orientations are inclined at approximately 45° with respect to axis 16 and circumferential direction 18.

The piston ring 10 having such fiber orientations is particularly stiff radially on the inside along the inner peripheral surface 32, less stiff in the middle and less stiff radially on the outside along the outer peripheral surface 38.

The opposite applies to the piston ring 10 according to 13A until 13C . Here are the respective orientations of the fibers 14 within the layers 36 to 40 in comparison to the variant according to 12A until 12C Radially inside and radially outside are exactly opposite. The piston ring 10 produced in this way has a high rigidity on the outer peripheral surface 34, a lower rigidity in the middle and an even lower rigidity on the inner peripheral surface 32.

By way of example, groups of figures 14 and 15 show variants of the piston ring 10 in which, as explained, only two layers 36 and 40 are present. Another difference to the variants described so far is that in one layer 36 or 40 fibers 14 with two different orientations are present, with 40 or 38 fibers 14 with only one orientation being present in the other layer.

To produce these piston rings, for example, a fiber braid or fabric can be combined with a fiber winding.

The embodiment according to 14A and 14B has fibers 14 aligned radially on the inside in two orientations (essentially axial and circumferential), as a result of which the piston ring 10 has a high level of rigidity on the inner peripheral surface 32. In the layer 40 on the radial outside, the fibers 14 are aligned approximately at an angle of 45° with respect to the axis 16, so that the piston ring 10 is less rigid in the outer peripheral surface 34.

In the embodiment according to 15A and 15B the fibers 14 in the layer 36 are approximately axially aligned; in the layer 40 there are two different orientations with an inclination with respect to the axis 16 of approximately 45 ° each.

In this way, for example, a piston ring 10 can be produced which is stiffer on the radial outside than on the radial inside.

In all variants of the piston ring 10 according to the invention described here, the ring joint 22 can be designed, for example, in one of the ways described below.

For example, a straight ring joint 22 according to 16 intended.

For example, oblique ring joints 22 are in right-hand design or in left-hand design according to 17 or. 18 intended.

For example, an annular joint 22 that is overlapped in the axial direction is according to 19 intended.

For example, a gas-tight ring joint 22 with overlap in the axial and radial directions is according to 20 intended.

For example, a ring joint 22 is like a compression ring with a tangential joint 21 intended.

For example, a ring joint is like a compression ring with a gas-tight, interlocked joint 22 provided, in which an overlap in the circumferential direction 18, the radial direction 20 and an additional hooking are provided.

For example, a ring joint 22 is like a gas-tight joint with a rectangular recess 23 intended. For example, an overlap is provided in the axial direction and in the radial direction.

For example, the butt ends on the end faces 26 according to 24 until 26 worked free.

For example, a ring joint 22 is like a compression ring with a hooked joint 27 provided, in which there is an overlap in the axial direction.

The 28 until 30 show schematically sections of the outer peripheral surface 34 adjacent to a piston receptacle 52, for example in the form of a piston liner 54. A piston, not shown in the drawing, which is surrounded by the piston ring 10, can be moved axially back and forth in the piston liner 54.

The piston ring 10 has the variants according to 28 until 30 Grooves 56 are preferably continuous along the outer peripheral surface 34. The grooves 56 can have different cross sections, for example rectangular, triangular or (not shown) rounded cross sections.

A labyrinth seal can be provided between the piston ring 10 and the piston liner 54 via the grooves 56.

The piston ring 10 can, as in the variant according to 30 shown, have at least one oil scraper groove 58.

The grooves 56 and 58 can be formed on the piston ring 10, for example during post-processing by grinding or milling.

31 shows a schematic representation of a variant of the piston ring 10, in which grooves 60 are formed on the end faces 26 of the ring joint 22. The grooves 60 are arranged on the opposite end faces 26 in such a way that a labyrinth seal can be achieved at the ring joint 22 to reduce blow-by. The grooves 60 can, for example, have a rectangular, triangular or (not shown) round cross section.

The grooves 60 can also be manufactured, for example, by post-processing by grinding or milling the piston ring 10.

The 32 shows a schematic partial representation with the reference number 62 Advantageous embodiment of a free piston device according to the invention. The free-piston device 62 comprises a free-piston engine 64, which is an advantageous embodiment of a piston engine 66 according to the invention. The free-piston engine 64 includes, for example, the piston receptacle 52, designed as a piston liner 54.

A combustion piston 68 is accommodated in the piston receptacle 62, on which at least one piston ring 10 according to the invention is arranged.

The combustion piston 68 can be moved back and forth along an axis 70, which coincides with the axis 16, of the piston receptacle 52. The combustion piston 68 delimits a combustion chamber 74 with a piston surface 72. In the combustion chamber 74, a fuel-air mixture can be ignited under expansion, whereby the combustion piston 68 is moved.

The advantage of using a C/C-SiC piston ring as a compression-compression ring with a relatively small ring joint 22 is that a sufficiently good seal of the combustion chamber of a piston engine can be achieved. In particular, a second compression ring can preferably be saved. An oil scraper ring, possibly also made of C/C-SiC, can be designed in such a way that only the smallest possible amount of oil is still present on the piston receptacle, due to the lubricating properties of the free carbon phase of the piston ring. As a result, it can be provided that the frequent second function of the usually second compression ring, fine adjustments of the oil quantity, is no longer necessary.

The advantage of such a design is that the piston can be made shorter and is lighter. This can result in a reduction in the free mass forces and the engine can be built with a smaller space requirement. Such an engine can have a lower weight and the center of gravity of the engine can be lowered (for example in a motor vehicle). This can include advantages, for example, in the crash behavior of a vehicle. Overall, the entire vehicle structure can be made lighter, which enables secondary fuel savings.

The piston ring according to the invention can be designed in one piece or in several parts. A multi-part design is advantageous, for example, in an application where the expansion of the piston ring during assembly could not be sufficiently guaranteed, even with the relative orientation of the fibers 14 causing the “lowest” stiffness. For example, in this case of a multi-part piston ring, it can be provided that the deformation section 28 is not diametrically opposite the expansion opening 24 with respect to the axis 16, but rather has an angular distance of less than 180 ° depending on the extent of the individual segments of the piston ring along the circumferential direction 18. This is expressly reserved for the present invention, especially in the case of a one-piece piston ring.

For a more detailed explanation of the manufacturing process for the piston ring according to the invention, see first 33 referred. This shows a core 78 that can be rotated about an axis 76 and a winding device 80 with which fibers 14 can be provided as an endless material, for example by means of a roving. An angle at which the fiber 14 can be applied to the rotating core 78 can be varied. By moving the winding device 80 parallel to the axis 76, fibers 14 can be arranged to form a body 82 in the form of a vertical circular cylinder with the axis 16. In the circumferential direction of the axis 16, different orientations of the fibers 14, along the radial direction 20, can be achieved at least over a predetermined or predeterminable angular range by varying the angle at which the winding takes place.

During winding, for example, a first, inner layer 36 with a predetermined orientation of the fibers 14 is formed. At least a second layer can then be formed radially on the outside with a different orientation of the fibers 14.

Matrix material for forming the matrix 12 for the fibers 14 can be provided by impregnating the body 12 after the winding process. Alternatively, pre-soaked fibers can be provided.

After the matrix 12 has hardened, the body 32 can be divided axially into individual rings. If necessary, ring joints 22 can be formed with the expansion openings 24.

It is conceivable that the body 82 or the individual rings resulting from segmentation or the piston rings with an existing ring joint 22 are reworked after the matrix 12 has hardened. During post-processing, the outer peripheral surface 34 in particular can be ground. Alternatively or additionally, for example, the grooves 56, 58 or 60 can be formed.

34 shows one of the 33 similar device in which a further winding device 84 is used. This gives the possibility to apply a braid to the core 78 by winding fibers 14 with different orientations onto the core 78 with each winding device 80, 84. At least one of the fiber orientations can then be changed in a further layer.

35 shows schematically a core 86 which has an axis 88. Several sheets 90 of a fiber material 92 can be applied to the core 86 one above the other in such a way that layers with different orientations or even several different orientations of the fibers 14 are created.

The webs 90 can, for example, be fabrics of fibers, as shown in the WO 2018/234244 A1 are described.

In a different type of production, sheets 90 made of fiber fleece 94 are used. The 36 until 38 show examples of related fiber fleeces 94.

36 shows a fiber fleece, designed as a parallel fleece 94 with longitudinally oriented fibers. The fiber directions within the fleece may differ. However, the fiber fleece 94 has a preferred direction symbolized by an arrow 96.

37 shows a fiber fleece 94, which is a parallel fleece with a transverse orientation. Arrows 98 and 99 indicate preferred directions of the fibers 14 within the fiber fleece 94.

38 shows a fiber fleece 94, designed as a cross-layer fleece with longitudinal and transverse orientation. For example, the fibers 14 may have preferred directions indicated by arrows 96, 98 and 99.

Depending on the orientation in which webs 90 are placed one on top of the other, different layers of fibers 14 with different orientations along the thickness direction 20 in the piston ring 10 can in particular be achieved.

It is understood that when winding, braiding, using woven fiber material 92 and/or woven fiber fleece 94, more than just one layer of fibers 14 with identical orientation are used for production, in which case several layers together form one of the layers.

Reference symbol list

10

Piston ring

12

matrix

14

fiber

16

axis

18

Circumferential direction

20

radial direction/thickness direction

22

Ring push

24

expansion opening

26

front side

28

deformation section

30

Angle range

32

Inner peripheral surface

34

Outer peripheral surface

36, 38, 40

layer

42

Arrow axial direction

44

Arrow circumferential direction

46, 48

angle

50

Fabric/braid

52

Piston mount

54

Piston liner

56

Nut

58

Oil scraper groove

60

Nut

62

Free piston device

64

Free piston engine

66

Piston engine

68

Combustion piston

70

axis

72

Piston area

74

combustion chamber

76

axis

78

core

80

Winding device

82

Body

84

Winding device

86

core

88

axis

90

Train

92

Fiber material

94

Non-woven fabric

96, 98, 99

Arrows preferred direction

Claims (19)

Piston ring made of a fiber composite material with a matrix (12) and fibers (14) embedded therein, which piston ring (10) defines an axis (16) and comprises an inner circumferential surface (32), an outer circumferential surface (34) spaced radially therefrom and an expansion opening (24), the piston ring (10) enlarging the expansion opening (24) in the circumferential direction ( 18) the axis (16) can be expanded, wherein the fibers (14) on the piston ring (10) have different orientations in sections, wherein the fibers (14), at least on a deformation section (28) arranged at a distance from the expansion opening (24), have different orientations along a thickness direction (20) of the piston ring (10) radially from the inner peripheral surface (32) to the outer peripheral surface (34). , and wherein at least one recess for forming a labyrinth seal with a corresponding end face (26) of the piston ring (10) is provided on at least one end face (26) of the piston ring (10) delimiting the expansion opening (24). Piston ring after Claim 1 , characterized in that the deformation section (28) lies opposite the expansion opening (24) with respect to the axis (16). Piston ring after Claim 1 or 2 , characterized in that an angle (46, 48) of the orientation of the fibers (14) with respect to the axial direction adjacent to the inner peripheral surface (32) is larger than adjacent to the outer peripheral surface (34), is smaller than on the outer peripheral surface (34), or is the same size or substantially the same size as on the outer peripheral surface (34). Piston ring according to one of the preceding claims, characterized in that an orientation of the fibers (14) adjacent to the inner peripheral surface (32) and / or adjacent to the outer peripheral surface (34) includes an angle (46, 48) with the axial direction, which is one of the The following is: - about 10° to 80°, preferably about 20° to 70°, preferably about 30° to 60°; - less than about 10° to about 0°; - more than about 80° to about 90°. Piston ring according to one of the preceding claims, characterized in that the rigidity of the piston ring (10), at least at the deformation section (28), adjacent to the outer peripheral surface (34) is higher than adjacent to the inner peripheral surface (32), or that the rigidity adjacent to the inner peripheral surface (32) is higher than adjacent to the outer peripheral surface (34). Piston ring according to one of the preceding claims, characterized in that the rigidity of the piston ring (10), at least at the deformation section (28), adjacent to the inner peripheral surface (32) is the same or substantially the same as adjacent to the outer peripheral surface (34) or different therefrom , and/or each larger or smaller than in a radially intermediate region of the piston ring (10). Piston ring according to one of the preceding claims, characterized in that the orientations of the fibers (14), along the thickness direction (20), in the entire circumferential direction (18), in particular to form different rigidities of the piston ring (10), differ from one another. Piston ring according to one of the preceding claims, characterized in that the piston ring (10) has two or more adjacent or merging layers (36, 38, 40) along the thickness direction (20), the orientations of the fibers (14) being within a respective one Layer (36, 38, 40) are identical or substantially identical, preferably along the entire circumferential direction (18). Piston ring after Claim 8 , characterized in that within a respective layer (36, 38, 40) there is only one orientation of the fibers (14) or two or more orientations, in particular two orientations in the case of a fiber fabric (50) or fiber mesh (50). Piston ring after Claim 8 or 9 , characterized in that the respective orientation of the fibers (14) is a preferred orientation of fibers or that the respective orientation is identical for all fibers (14) within a layer (36, 38, 40). Piston ring according to one of the Claims 1 until 7 , characterized in that the orientations of the fibers (14) vary continuously along the thickness direction (20). Piston ring according to one of the preceding claims, characterized in that the fibers (14) are each aligned in a lateral surface around the axis (16). Piston ring according to one of the preceding claims, characterized in that at least one of the following applies: - the fibers (14) are wound fibers (14); - the fibers (14) form a fiber braid (50) or a fiber fabric (50); - The fibers (14) are arranged in layers (36, 38, 40) radially one above the other with a respective orientation. Piston ring according to one of the preceding claims, characterized in that the matrix (12) comprises carbide and a free carbon phase and/or that the fiber composite material is C/C-SiC. Piston ring according to one of the preceding claims, characterized in that the piston ring (10) has on the outer peripheral surface (34) at least one groove (56, 60) which runs at least partially in the circumferential direction (18) to form a labyrinth seal with a piston receptacle (52). Piston machine, comprising at least one piston which can be moved back and forth in a piston receptacle (52), on which at least one piston ring (10) according to one of the preceding claims is arranged, wherein the piston machine is in particular a motor or a compressor or comprises such. Method for producing a piston ring according to one of Claims 1 until 15 , the method comprising: - Arranging fibers to form a body in the form of a particularly vertical circular cylinder defining an axis in such a way that at least two layers of fibers are arranged radially with respect to the axis and the fibers in the circumferential direction of the axis over a predetermined or predeterminable angular range have different orientations along a radial direction; - Providing and curing a matrix for the fibers; and - Forming at least one recess on at least one end face of the piston ring delimiting the expansion opening to form a labyrinth seal with a corresponding end face of the piston ring. Procedure according to Claim 17 , characterized in that the arranging of the fibers occurs via at least one of the following: - winding the fibers onto a core, the fiber orientation being changed over an angle at which the fibers are wound onto the core; - Braiding the fibers on a core, changing the fiber orientation via an angle at which the fibers are braided onto the core; - providing two or more layers of fibrous fabric to be placed on the core, with superimposed layers being placed on the core at different angles; - Providing two or more layers of fiber felt, which have a respective preferred orientation of the fibers contained therein; - 3D printing of matrix material containing fibers; - Arrangement and targeted positioning of individual fibers on a core using tailored fiber placement (TFP); - Providing and positioning fiber strands using a pultrusion device; - Providing by means of an injection molding process, whereby fibers are embedded in matrix material. Procedure according to Claim 17 or 18 , characterized in that the method comprises at least one of the following steps: - the fibers are provided pre-impregnated with matrix material in the arranging step, or the fibers are infiltrated with a matrix material after arranging; - the body is axially divided into a plurality of rings after the matrix material has hardened; - an expansion opening is formed on the body after hardening or when arranging the fibers; - The body or the piston ring are reworked, in particular rework is carried out by grinding and / or introducing at least one groove on the outer circumferential surface and / or introducing at least one recess on an end face delimiting the expansion opening.

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