Abstract: A piston ring for an internal-combustion engine may include a body having a substantially annular external surface and a physical vapor deposition coating layer disposed on the external surface. The body may include a gap defined between a first end and a second end. The piston ring may also include a first half in a region of the gap and a second half opposite the first half. The coating layer of the first half may have a thickness gradient, and the coating layer may define a greater thickness in a vicinity of the first end and the second end and a reduced thickness in regions further away from the vicinity of the first end and the second end. The coating layer of the second half may have a uniform thickness.

Abstract: A piston ring for an internal-combustion engine may include a body having a substantially annular external surface and a physical vapor deposition coating layer disposed on the external surface. The body may include a gap defined between a first end and a second end. The piston ring may also include a first half in a region of the gap and a second half opposite the first half. The coating layer of the first half may have a thickness gradient, and the coating layer may define a greater thickness in a vicinity of the first end and the second end and a reduced thickness in regions further away from the vicinity of the first end and the second end. The coating layer of the second half may have a uniform thickness.

Abstract: An oil control ring for internal combustion engines, formed by a ferrous body having two external contact surfaces where each surface contains first and second extremity edges, two tilted faces where each tilted face starts from the respective second edge, a peripheral transversal section directed at the cylinder wall and an internal circular section directed at the side of the piston, where the projections of contact are directed, so that the respective tilted faces are turned facing the other, symmetrically, in a preferred concretization. The ring allows the maintenance of appropriate levels of contact pressure, even under reduced expanding loadings due to the use of profile that brings reduced contact of the ring with the cylinder interface. Additionally, it brings better dynamic stability and consequent distribution of the contact pressure of the set. It also makes it possible to apply superficial hardening treatments on oil rings with reduced contact surface.