An outer peripheral surface of a piston ring has a cut surface provided to form a cutout portion between an outer peripheral end portion and a lower surface, the cut surface includes a curved concave surface, an inclination angle of a tangent of the curved concave surface at a point closest to the combustion chamber side on the curved concave surface, with respect to a first virtual line extending in parallel to the lower surface is equal to or greater than 5? and equal to or less than 50?, and in a case where an axial direction width of the piston ring is set as h1, and an axial direction width of the cut surface is set as H, H/h1 is equal to or greater than 0.2 and equal to or less than 0.4.

An internal combustion engine includes a cylinder defining a combustion chamber enclosed by a cylinder wall, a piston that is arranged inside the combustion chamber and moveable in a reciprocating motion away from and towards a crankshaft, and at least one first scraper ring defining an oil scraper ring that is arranged between the piston and the cylinder wall and configured to scrape oil off from the cylinder wall when the piston moves towards the crankshaft. The internal combustion engine further includes at least one second scraper ring defining a condensation fluid scraper ring that is arranged between the piston and the cylinder wall and configured to scrape a condensation fluid off from the cylinder wall when the piston moves away from the crankshaft.

An outer peripheral surface of a piston ring has a cut surface provided to form a cutout portion between an outer peripheral end portion and a lower surface, the cut surface includes a curved concave surface, an inclination angle of a tangent of the curved concave surface at a point closest to the combustion chamber side on the curved concave surface, with respect to a first virtual line extending in parallel to the lower surface is equal to or greater than 5? and equal to or less than 50?, and in a case where an axial direction width of the piston ring is set as h1, and an axial direction width of the cut surface is set as H, H/h1 is equal to or greater than 0.2 and equal to or less than 0.4.

A combination of piston rings assembled to a piston of an internal combustion engine includes four compression rings. An outer peripheral surface of a first compression ring includes a barrel surface, an outer peripheral surface of a second compression ring includes an outer peripheral end portion and a taper surface, an outer peripheral surface of a third compression ring includes an outer peripheral end portion and a taper surface, and an outer peripheral surface of a fourth compression ring includes an outer peripheral end portion and a taper surface.

An integrally formed piston has a crown portion having an upper crown surface and an undercrown surface. A ring belt extends from the undercrown surface at a periphery thereof. The ring belt includes an uppermost ring land and at least one oil galley contoured to extend around at least two surfaces of the uppermost ring land. The oil galley has an opening at the undercrown surface for receiving a cooling fluid therein for cooling the uppermost ring land. A skirt extends from the undercrown surface and the ring belt and has a plurality of stiffening features arranged in a truss formation. At least one of the plurality of stiffening features has an I-beam cross-section and another of the plurality of stiffening features has a negative draft angle.

An integrally formed piston has a crown portion having an upper crown surface and an undercrown surface. A ring belt extends from the undercrown surface at a periphery thereof. The ring belt includes an uppermost ring land and at least one oil galley contoured to extend around at least two surfaces of the uppermost ring land. The oil galley has an opening at the undercrown surface for receiving a cooling fluid therein for cooling the uppermost ring land. A skirt extends from the undercrown surface and the ring belt and has a plurality of stiffening features arranged in a truss formation. At least one of the plurality of stiffening features has an I-beam cross-section and another of the plurality of stiffening features has a negative draft angle.

A piston ring is formed from a steel substrate consisting of the carbon in a range of 0.80-0.95 wt. %, silicon in a range of 0.30-0.55 wt. %, manganese in a range of 0.25-0.5 wt. %, phosphorus in a range of up to 0.04 wt. %, sulfur in a range of up to 0.04 wt. %, chromium in a range of 17-18 wt. %, molybdenum in a range of 0.70-1.25 wt. %, vanadium in a range of 0.05-0.15%, the remainder iron. The ring has been through hardened and tempered so that it has a hardness of 46-54 HRC. A coating is then applied via PVD or other suitable methods onto the ring surface to create the finished piston ring.

A liquid epoxy resin, a powdered metal and a hardening agent are provided as a filling material (S) and poured into an insert hole (82). The filling material (S) is in a liquid state under a normal temperature so as to make the filling material (S) handle easily in the filling work. The filling material (S) is hardened at a clearance between a bushing tool (12) and the insert hole (82). The filling material (S) is placed between the bushing tool (12) and the insert hole (82) to enhance a heat-conductivity therebetween. By heat treating a metallic mold die 80, it is possible to char the epoxy resin. This makes it possible to deposit the powdered metal (copper or the like) over an entire area of the clearance so as to highly enhance the heat-conductivity.

A seal ring for an electrochemical processor does not slip or deflect laterally when pressed against a wafer surface. The seal ring may be on a rotor of the processor, with the seal ring having an outer wall joined to a tip arc through an end. The outer wall may be a straight wall. A relatively rigid support ring may be attached to the seal ring, to provide a more precise sealing dimension. Knife edge seal rings that slip or deflect laterally on the wafer surface may also be used. In these designs, the slipping is substantially uniform and consistent, resulting in improved performance.

A sealing arrangement includes a first and a second machine part movable relative to each other along a motional axis. A sealing element is arranged in a press fit in a plurality of grooves of a seal-holding structure of the first machine part. A sealing lip of the sealing element extends away from the seal-holding structure in the axial direction. A pretensioning element is disposed in a retaining groove of the first machine part. The sealing lip is pretensioned against a sealing surface of the second machine part in order to seal off a high-pressure region. The retaining groove has a wedge guide surface for the pretensioning element, which wedge guide surface is arranged running obliquely at an angle , where <90, to the motional axis. The pretensioning element is movable against and along the wedge guide surface to pretension the sealing lip against the sealing surface.