A piston for an internal combustion engine including a cooling gallery and a complex combustion surface is provided. The piston includes an upper crown member joined to a lower member, for example by hybrid induction welding. A complex combustion bowl is formed in the upper crown member by forging. The combustion bowl includes at least one protrusion, and typically a plurality of protrusions spaced from one another. After the forging step and before the joining step, portions of an undercrown surface located opposite the spaces between the protrusions are machined, and portions located directly opposite the protrusions are left as-forged. The crown member is joined to the lower member, for example by hybrid induction welding.

Disclosed is an internal combustion engine piston wherein at least one space is formed into which a coolant is installed. In one example, the coolant is first introduced into a coolant container and the coolant container is thereafter inserted into the at least one space in the piston. In one example, the coolant is an alkali metal consisting of sodium.

Disclosed is an internal combustion engine piston wherein at least one space is formed into which a coolant is installed. In one example, the coolant is first introduced into a coolant container and the coolant container is thereafter inserted into the at least one space in the piston. In one example, the coolant is an alkali metal consisting of sodium.

A piston can include a skirt, a crown, and a cooling gallery. The skirt can have an upper body portion. The crown can be formed at the upper body portion. A wall can be formed underneath the crown so as to define a cooling gallery within the piston. The cooling gallery includes cooling gallery peripheral portion and a cooling gallery central portion. The cooling gallery can be configured to receive and to retain an amount of cooling fluid and to cause movement thereof within the cooling gallery between a cooling gallery peripheral portion and a cooling gallery central portion as the piston travels between top dead center and bottom dead center so as to cool both the piston outer region and the piston center region.

A piston can include a skirt, a crown, and a cooling gallery. The skirt can have an upper body portion. The crown can be formed at the upper body portion. A wall can be formed underneath the crown so as to define a cooling gallery within the piston. The cooling gallery includes cooling gallery peripheral portion and a cooling gallery central portion. The cooling gallery can be configured to receive and to retain an amount of cooling fluid and to cause movement thereof within the cooling gallery between a cooling gallery peripheral portion and a cooling gallery central portion as the piston travels between top dead center and bottom dead center so as to cool both the piston outer region and the piston center region.

A steel piston with anti-coking design features is provided. The piston includes an upper crown portion and a lower crown portion forming an outer cooling gallery therebetween. The outer cooling gallery is substantially closed except for an oil inlet, oil outlet, and optional oil passage(s) to a central cooling gallery. According to one embodiment, at least one anti-coking insert is disposed in the outer cooling gallery and sized to prevent escaping through the oil inlet or the oil outlet. For example, the insert(s) can comprise a helical coil, a plurality of steel balls, coil springs, or chips formed of polymer with abrasive filler. Alternatively, an outer gallery floor to the outer cooling gallery includes a plurality of anti-coking openings disposed sequentially in decreasing spaced relation from one another, or anti-coking openings with varying lengths.

A steel piston with anti-coking design features is provided. The piston includes an upper crown portion and a lower crown portion forming an outer cooling gallery therebetween. The outer cooling gallery is substantially closed except for an oil inlet, oil outlet, and optional oil passage(s) to a central cooling gallery. According to one embodiment, at least one anti-coking insert is disposed in the outer cooling gallery and sized to prevent escaping through the oil inlet or the oil outlet. For example, the insert(s) can comprise a helical coil, a plurality of steel balls, coil springs, or chips formed of polymer with abrasive filler. Alternatively, an outer gallery floor to the outer cooling gallery includes a plurality of anti-coking openings disposed sequentially in decreasing spaced relation from one another, or anti-coking openings with varying lengths.

Provided is a piston for an internal combustion engine. The piston includes a body including, at an upper part of the body, a crown including a combustion chamber where fuel is burnt and including, at a lower part of the body, a piston pin boss into which a piston pin is inserted and a skirt corresponding to a cylinder wall, and a cooling channel including a refrigerant channel, a refrigerant inlet provided at a side of the refrigerant channel, and a refrigerant outlet provided at the other side of the refrigerant channel, wherein a cross section of the cooling channel has an overall elliptic shape to reduce stress occurring at an upper side of the cooling channel when the fuel is burnt in the internal combustion engine, and at least one of arcs of the ellipse is configured as a first elliptical arc of a quadratic curve.

Provided is a piston for an internal combustion engine. The piston includes a body including, at an upper part of the body, a crown including a combustion chamber where fuel is burnt and including, at a lower part of the body, a piston pin boss into which a piston pin is inserted and a skirt corresponding to a cylinder wall, and a cooling channel including a refrigerant channel, a refrigerant inlet provided at a side of the refrigerant channel, and a refrigerant outlet provided at the other side of the refrigerant channel, wherein a cross section of the cooling channel has an overall elliptic shape to reduce stress occurring at an upper side of the cooling channel when the fuel is burnt in the internal combustion engine, and at least one of arcs of the ellipse is configured as a first elliptical arc of a quadratic curve.

A piston for an internal combustion engine is provided. The piston includes a body having a cylindrical outer surface with a ring belt region including an annular uppermost ring groove and a lower ring groove extending into the outer surface. A top land extends from the uppermost ring groove to an upper combustion surface. The body has a pair of pin bosses with pin bores aligned with one another along a pin bore axis. A first piston ring is disposed in the uppermost ring groove and a second piston ring is disposed in the lower ring groove. The body has an annular sealed cooling gallery with a cooling medium contained therein. The sealed cooling gallery is configured in substantial radial alignment between the first and second piston rings to provide optimal cooling to the ring belt region, top land and upper combustion surface.