Abstract: A piston with an oil return channel may include a piston head, a piston skirt, and an oil return hole. The piston head may include a ring groove. The piston skirt may be connected to the piston head. The piston skirt may have a surface including a concave face window. A connection between the face window and the ring groove may form a residual ring bank. The oil return hole may be formed by milling on the residual ring bank. The oil return hole may connect the ring groove close to the piston skirt with the face window. A depth of the oil return hole may be greater than a depth of the ring groove.

Abstract: A cast piston for an internal combustion engine is made of an iron-based material and has windows in at least one side wall carrying a piston pin boss. The windows are asymmetric relative to one another on the side of the skirt walls.

Abstract: A piston for an internal combustion engine is provided. The piston includes a piston body which is made of steel. The piston body has a crown portion with an upper combustion surface, a pair of skirts which depend from the crown surface, a pair of pin bosses for receiving a wrist pin and a plurality of pin boss bridges which extend from the pin bosses to the skirts. Each of the pin boss bridges extends axially to a lower end which is opposite of the crown portion and has a rib with an increased thickness at its lower end. At least one of the pin boss bridges has a generally flat counter-bore surface for providing a reference location for machining of the piston body.

Abstract: In this piston, oil grooves 5 are provided in the selected parts of a surface of a skirt portion 3 which are liable to encounter the breakage of an oil film, and which are on the thrust side and anti-thrust side, and not in the parts of the surface of the skirt portion to which a load is imparted. The oil grooves 5 are formed in the positions higher than a piston pin 22 and lower than piston ring grooves 12, and cooling cavity 45 and oil grooves 5 communicate with each other by oil passages 47, the cooling cavity 45 and a lower open end 48 of a piston body 1 communicating with each other by an oil passage 46. Accordingly, even when the piston is inclined toward the anti-thrust direction, an oil is supplied to the clearances between outer members 7 and skirt portion 3, and the breakage of an oil film does not occur.

Abstract: A light-alloy piston for internal combustion engine, is formed in the piston head with a combustion chamber recess. The stresses which are induced at the rim of the combustion chamber recess by the ignition pressure are reduced by the provision of an inwardly extending blind hole in the portions between the ring groove for the lowermost compression ring and the top apex of the bores in the piston pin bosses.