The piston ring assembly having a first and a second endless sealing ring and an elastic ring carrier, the first and the second sealing ring extending in a circumferential direction (U) and each having an outer circumferential surface, the first sealing ring having a first center point (M1) with respect to its outer circumferential surface and the second sealing ring having a second center point (M2 ) with respect to its outer circumferential surface, the first and second sealing rings each having a longitudinal axis (L) running perpendicular to the circumferential direction (U), wherein the ring carrier runs in the circumferential direction (U), and wherein the ring carrier and the first and second sealing rings are designed to be mutually adapted in such a way that the first and second sealing rings are arranged one after the other in the ring carrier in the direction of the longitudinal axis (L), and in that their first and second centers (M1, M2) are arranged at a distance from one another radially with respect to the longitudinal axis (L), the sealing rings being pressed in opposite directions against the inner wall of a cylinder when the piston ring assembly is used in accordance with the invention.

The piston ring assembly having a first and a second endless sealing ring and an elastic ring carrier, the first and the second sealing ring extending in a circumferential direction (U) and each having an outer circumferential surface, the first sealing ring having a first center point (M1) with respect to its outer circumferential surface and the second sealing ring having a second center point (M2 ) with respect to its outer circumferential surface, the first and second sealing rings each having a longitudinal axis (L) running perpendicular to the circumferential direction (U), wherein the ring carrier runs in the circumferential direction (U), and wherein the ring carrier and the first and second sealing rings are designed to be mutually adapted in such a way that the first and second sealing rings are arranged one after the other in the ring carrier in the direction of the longitudinal axis (L), and in that their first and second centers (M1, M2) are arranged at a distance from one another radially with respect to the longitudinal axis (L), the sealing rings being pressed in opposite directions against the inner wall of a cylinder when the piston ring assembly is used in accordance with the invention.

A piston ring has a running surface, an inner surface, a lower ring flank, and an upper ring flank. A recess, extending across the perimeter in the shape of an internal angle, is located at the transition between the inner surface and the upper ring flank. The recess defines a conical first surface and a conical second surface at the piston ring. The first surface lies farther outward, when viewed in the radial direction, and farther above, when viewed in the axial direction, than the second surface. In an axial cross section, a first angle between the axial direction and the first surface lies in the range between 10° and 50°, and a second angle between the radial direction and the second surface lies in the range between 5° and 30°. A piston having a piston ring groove includes a projection on the groove bottom. A combination made from an above-mentioned piston ring and an above-mentioned piston are adapted to one another, so that the projection projects into the recess.

A piston ring has a running surface, an inner surface, a lower ring flank, and an upper ring flank. A recess, extending across the perimeter in the shape of an internal angle, is located at the transition between the inner surface and the upper ring flank. The recess defines a conical first surface and a conical second surface at the piston ring. The first surface lies farther outward, when viewed in the radial direction, and farther above, when viewed in the axial direction, than the second surface. In an axial cross section, a first angle between the axial direction and the first surface lies in the range between 10° and 50°, and a second angle between the radial direction and the second surface lies in the range between 5° and 30°. A piston having a piston ring groove includes a projection on the groove bottom. A combination made from an above-mentioned piston ring and an above-mentioned piston are adapted to one another, so that the projection projects into the recess.

A piston ring has a running surface, an inner surface, a lower ring flank, and an upper ring flank. A recess, extending across the perimeter in the shape of an internal angle, is located at the transition between the inner surface and the upper ring flank. The recess defines a conical first surface and a conical second surface at the piston ring. The first surface lies farther outward, when viewed in the radial direction, and farther above, when viewed in the axial direction, than the second surface. In an axial cross section, a first angle between the axial direction and the first surface lies in the range between 10° and 50°, and a second angle between the radial direction and the second surface lies in the range between 5° and 30°. A piston having a piston ring groove includes a projection on the groove bottom. A combination made from an above-mentioned piston ring and an above-mentioned piston are adapted to one another, so that the projection projects into the recess.

A piston ring has a running surface, an inner surface, a lower ring flank, and an upper ring flank. A recess, extending across the perimeter in the shape of an internal angle, is located at the transition between the inner surface and the upper ring flank. The recess defines a conical first surface and a conical second surface at the piston ring. The first surface lies farther outward, when viewed in the radial direction, and farther above, when viewed in the axial direction, than the second surface. In an axial cross section, a first angle between the axial direction and the first surface lies in the range between 10° and 50°, and a second angle between the radial direction and the second surface lies in the range between 5° and 30°. A piston having a piston ring groove includes a projection on the groove bottom. A combination made from an above-mentioned piston ring and an above-mentioned piston are adapted to one another, so that the projection projects into the recess.

A piston ring (2) having increased fatigue resistance includes a plastically deformable material. The piston ring (2) has a running face (4), which is delimited at the top by an upper running face edge (3) and at the bottom by a lower running face edge (1). Compressive stresses are introduced into the upper running face edge (3) and/or into the lower running face edge (1) along at least one part of the circumference, the compressive stresses having been produced by roller burnishing.

A piston ring (2) having increased fatigue resistance includes a plastically deformable material. The piston ring (2) has a running face (4), which is delimited at the top by an upper running face edge (3) and at the bottom by a lower running face edge (1). Compressive stresses are introduced into the upper running face edge (3) and/or into the lower running face edge (1) along at least one part of the circumference, the compressive stresses having been produced by roller burnishing.

A pump assembly, fluid machinery, and a heat exchange device. The pump assembly includes: a lower flange; a lower friction-reducing ring; a cylinder, the lower friction-reducing ring being disposed inside the cylinder, and the lower flange being disposed below the cylinder; and a piston assembly arranged inside the cylinder and includes a piston sleeve and a piston slidably arranged inside the piston sleeve. The lower friction-reducing ring has a central hole. A position-limiting protrusion is disposed on a surface of the piston sleeve, which faces the lower flange. The limiting protrusion extends into the central hole of the lower friction-reducing ring, fits and is limited by the lower flange.

The present invention relates to a two-part oil scraper ring, which comprises an L-shaped base body and an axial stabilization element. The L-shaped base body has a ring flank leg, which is pressed against a piston ring groove flank by the axial stabilization element, and a bearing surface leg, on which a scraping web is arranged. A twist compensation is attained by means of a suitable selectionand in particular variationof hearing surface leg length, ring flank leg length and axial position of the scraping web.