To provide a long-life compression ring without an increase in the outer peripheral abrasion near the gap regardless of the ring material or the presence or absence of the outer peripheral hard coating, in an annular compression ring having a pair of gap faces opposed to each other to form a free gap and a nominal diameter d1 equal to an inner diameter of a cylinder to which the compression ring is attached to along with a piston, a self tangential force is 5 N to 50 N, and a radius of curvature R1 and the nominal diameter d1 satisfy a relationship:

−0.01≤(2R1−d1)/d1<0.002

where the radius of curvature R1 is that of outer peripheral arcs of gap end portions in a free shape state before the compression ring is attached to the cylinder, and the gap end portions are defined in ranges between the gap faces and positions where a center angle from a midpoint of the free gap is 35°.

A back-up ring (1) for a gland seal includes at least two part ring portions (2,4). Each part ring portion comprises first (6, 10) and second (8, 12) ends. Each end has an undulating surface (22, 24) for overlapping in engagement with a corresponding undulating surface on an end of another part ring portion, to form the back-up ring (1). When the part ring portions (2,4) are assembled to form the back-up ring (1) and are held together by axial and/or radial compression, the engagement of the undulating surfaces (22, 24) restricts relative movement between the part ring portions. A seal assembly (34) including the back-up ring (1) is also disclosed.

A sealing assembly and a turbomachine including the sealing assembly are provided. The sealing assembly includes a sealing body configured to be inserted into an insertion hole of a second component adjacent to a first component, and a sealing protrusion, formed on one circumferential side of the sealing body, protruding toward one circumferential direction from the sealing body and configured to be inserted into a sealing groove formed on the other circumferential side of a sealing body of the first adjacent sealing assembly, the sealing body of the first adjacent sealing assembly being adjacent to the sealing body in a circumferential direction.

A sealing assembly and a turbomachine including the sealing assembly are provided. The sealing assembly includes a sealing body configured to be inserted into an insertion hole of a second component adjacent to a first component, and a sealing protrusion, formed on one circumferential side of the sealing body, protruding toward one circumferential direction from the sealing body and configured to be inserted into a sealing groove formed on the other circumferential side of a sealing body of the first adjacent sealing assembly, the sealing body of the first adjacent sealing assembly being adjacent to the sealing body in a circumferential direction.

Embodiments of a combination piston and piston ring to reduce the volume of a crevice defined between the circumferential wall of a cylinder and a portion of the outer wall of a piston within the cylinder, the portion extending down from the top of the piston. The combination piston and piston ring is configured such that pressurized fluid within the cylinder reliably urges a radial face of the piston ring to sealingly engage the circumferential wall of the cylinder, even as the piston reciprocates within the cylinder.

Embodiments of a combination piston and piston ring to reduce the volume of a crevice defined between the circumferential wall of a cylinder and a portion of the outer wall of a piston within the cylinder, the portion extending down from the top of the piston. The combination piston and piston ring is configured such that pressurized fluid within the cylinder reliably urges a radial face of the piston ring to sealingly engage the circumferential wall of the cylinder, even as the piston reciprocates within the cylinder.

The present invention is to provide a sealing device that has a small number of parts as three or less to achieve a more compact sealing device. The sealing device is combined an inner seal ring, an outer seal ring held in an outer circumferential holding groove of the inner seal ring, and a back ring. The outer seal ring satisfies a dimensional size relationship of T>A when T is the radial thickness dimension of the outer seal ring, G is the protrusion gap dimension, R is the radial width dimension of the chamfered sections on the edges of the open side of the seal installation groove, and A is the sum of the protrusion gap dimension G and the radial width dimension R of the chamfered sections on the edges of the open side.

The present invention is to provide a sealing device that has a small number of parts as three or less to achieve a more compact sealing device. The sealing device is combined an inner seal ring, an outer seal ring held in an outer circumferential holding groove of the inner seal ring, and a back ring. The outer seal ring satisfies a dimensional size relationship of T>A when T is the radial thickness dimension of the outer seal ring, G is the protrusion gap dimension, R is the radial width dimension of the chamfered sections on the edges of the open side of the seal installation groove, and A is the sum of the protrusion gap dimension G and the radial width dimension R of the chamfered sections on the edges of the open side.

A scraper ring for a piston includes a top surface, a bottom surface, an inner surface, and an outer surface. The top surface has a first planar portion and a first angled portion. The bottom surface has a second planar portion and a second angled portion. The second angled portion is configured to slidably contact the first angled portion to adjust a diameter of the scraper ring. The inner surface connects the top surface to the bottom surface. The outer surface is opposite to the top surface and is configured to form 360 degrees of contact with a wall of a cylinder to substantially limit an amount of oil entering a combustion chamber of the cylinder.

A scraper ring for a piston includes a top surface, a bottom surface, an inner surface, and an outer surface. The top surface has a first planar portion and a first angled portion. The bottom surface has a second planar portion and a second angled portion. The second angled portion is configured to slidably contact the first angled portion to adjust a diameter of the scraper ring. The inner surface connects the top surface to the bottom surface. The outer surface is opposite to the top surface and is configured to form 360 degrees of contact with a wall of a cylinder to substantially limit an amount of oil entering a combustion chamber of the cylinder.