Piston ring and piston with internal groove sealing

A piston ring and piston combination,

• the piston ring including a running surface, an inner surface, a lower ring flank, and an upper ring flank;
• wherein a recess, extending across the perimeter in the shape of an internal angle, is located at a transition between the inner surface and the upper ring flank;
• wherein the recess defines a conical first surface and a conical second surface, wherein 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;
• wherein, 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°;
• the piston including a piston ring groove comprising a groove bottom and a lower groove flank, wherein a projection is arranged at an upper end of the groove bottom of the piston ring groove;
• wherein the projection has a conical first projection surface and a conical second projection surface, wherein the first projection surface lies farther outward, when viewed in the radial direction, and farther above, when viewed in the axial direction, than the second projection surface, wherein, in an axial cross section, a third angle between the axial direction and the first projection surface lies in the range between 10° and 50°, and a fourth anele between the radial direction and the second projection surface lies in the range between 5° and 30°;
• wherein the recess and the projection are designed such that, when the piston ring is mounted in the piston ring groove:
• the projection projects into the recess, the second surface extends parallel to the second projection surface, and the first surface extends parallel to the first projection surface or the first angle between the axial direction and the first surface is greater than the third angle between the axial direction and the first projection surface;
• wherein an inner edge line of the first surface has a greater radius than an inner edge line of the first projection surface;
• and
• wherein a difference of the radii of the inner edge line of the first surface and the inner edge line of the first projection surface lies in the range from 15 μm to 300 μm.

A piston ring and piston combination,

• the piston ring including a running surface, an inner surface, a lower ring flank, and an upper ring flank;
• wherein a recess, extending across the perimeter in the shape of an internal angle, is located at a transition between the inner surface and the upper ring flank;
• wherein the recess defines a conical first surface and a conical second surface, wherein 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;
• wherein, 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°;
• the piston including a piston ring groove comprising a groove bottom and a lower groove flank, wherein a projection is arranged at an upper end of the groove bottom of the piston ring groove;
• wherein the projection has a conical first projection surface and a conical second projection surface, wherein the first projection surface lies farther outward, when viewed in the radial direction, and farther above, when viewed in the axial direction, than the second projection surface, wherein, in an axial cross section, a third angle between the axial direction and the first projection surface lies in the range between 10° and 50°, and a fourth angle between the radial direction and the second projection surface lies in the range between 5° and 30°;
• wherein the recess and the projection are designed such that, when the piston ring is mounted in the piston ring groove:
• the projection projects into the recess, the second surface extends parallel to the second projection surface, and the first surface extends parallel to the first projection surface or the first angle between the axial direction and the first surface is greater than the third angle between the axial direction and the first projection surface;
• wherein, when the piston ring is mounted in the piston ring groove and the second surface contacts the second projection surface, an axial distance exists between the first surface and the first projection surface;
• and
• wherein the piston ring groove additionally comprises an upper groove flank, and wherein, when the piston ring is mounted in the piston ring groove and the second surface contacts the second projection surface, an axial distance exists between the upper ring flank and the upper groove flank, which lies in the range of 0.9-1.5 times the axial distance between the first surface, and the first projection surface.