The piston includes a pair of pin bores that are aligned with one another along a pin bore axis. The piston further includes a crown that has a top combustion surface with an outer rim and a ring belt that depends from the outer rim. The ring belt includes a top land and a first ring groove for receiving a piston ring. At least one recess is formed into the top land and extends from the top combustion surface less than a full distance from the top combustion surface to the first ring groove.

The piston includes a pair of pin bores that are aligned with one another along a pin bore axis. The piston further includes a crown that has a top combustion surface with an outer rim and a ring belt that depends from the outer rim. The ring belt includes a top land and a first ring groove for receiving a piston ring. At least one recess is formed into the top land and extends from the top combustion surface less than a full distance from the top combustion surface to the first ring groove.

A damper device includes a cylinder including an attachment portion and a piston including an attachment portion. The attachment portion of at least one of the cylinder and the piston includes an elastic portion which urges a pin member inserted therein in an axial direction and a radial direction. The elastic portion includes an axial abutment portion which abuts on a large-diameter portion of the pin member protruding radially outward from an outer peripheral surface of the pin member; and a radial abutment portion which abuts on the outer peripheral surface of the pin member.

A damper device includes a cylinder including an attachment portion and a piston including an attachment portion. The attachment portion of at least one of the cylinder and the piston includes an elastic portion which urges a pin member inserted therein in an axial direction and a radial direction. The elastic portion includes an axial abutment portion which abuts on a large-diameter portion of the pin member protruding radially outward from an outer peripheral surface of the pin member; and a radial abutment portion which abuts on the outer peripheral surface of the pin member.

An engine piston assembly includes a piston with two opposing boss bores, a first interlocking piston button with at least one interlocking protrusion compatible with at least one interlocking recess in the first boss bore, and a second interlocking piston button with at least one interlocking protrusion compatible with at least one interlocking recess in the second boss bore. The interlocking protrusions serve to prevent the buttons from rotating inside the boss bores and deforming an oil control ring inside an oil control ring groove of the piston assembly.

An engine piston assembly includes a piston with two opposing boss bores, a first interlocking piston button with at least one interlocking protrusion compatible with at least one interlocking recess in the first boss bore, and a second interlocking piston button with at least one interlocking protrusion compatible with at least one interlocking recess in the second boss bore. The interlocking protrusions serve to prevent the buttons from rotating inside the boss bores and deforming an oil control ring inside an oil control ring groove of the piston assembly.

An improved piston pin retention button device having a body portion comprised of both a generally cylindrical portion and a surface, such as a planar surface, for mating engagement with a corresponding surface formed in a piston device. The inclusion of both the surface on the body portion and the corresponding surface in said piston device prevent rotation of the button device in the piston device. Other embodiments of a piston pin retention button device are also disclosed and prevent the unwanted rotation of the button device in the piston device, and permit the oil ring to function as designed.

An improved piston pin retention button device having a body portion comprised of both a generally cylindrical portion and a surface, such as a planar surface, for mating engagement with a corresponding surface formed in a piston device. The inclusion of both the surface on the body portion and the corresponding surface in said piston device prevent rotation of the button device in the piston device. Other embodiments of a piston pin retention button device are also disclosed and prevent the unwanted rotation of the button device in the piston device, and permit the oil ring to function as designed.

A piston assembly includes a piston head for reciprocating back and forth within a cylinder of an engine, an upper rod coupled to the piston head at one longitudinal end of the upper rod and fixed relative to the piston head, and a lower rod rotatably coupled to an opposite longitudinal end of the upper rod, the lower rod configured to pivot about the opposite longitudinal end of the upper rod. The lower rod is configured to couple to a crankshaft at a longitudinal end of the lower rod opposite the upper rod. Methods of forming a piston assembly and engines incorporating such piston assemblies are also disclosed.

A piston assembly includes a piston head for reciprocating back and forth within a cylinder of an engine, an upper rod coupled to the piston head at one longitudinal end of the upper rod and fixed relative to the piston head, and a lower rod rotatably coupled to an opposite longitudinal end of the upper rod, the lower rod configured to pivot about the opposite longitudinal end of the upper rod. The lower rod is configured to couple to a crankshaft at a longitudinal end of the lower rod opposite the upper rod. Methods of forming a piston assembly and engines incorporating such piston assemblies are also disclosed.