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.

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.

[Problem to be Solved] A space from a skirt to a side wall is uniformly deformed in a wide range without a bias. [Solution] A piston 1 has two pin bosses 3 disposed so as to face each other at an interval, a side wall 4 disposed on both sides of the pin boss 3, and a skirt 5 provided continuously to the side wall 4, and a pin hole 3a into which a piston pin 1a can be inserted is formed in the pin boss 3. Inner walls 10 of the side wall 4 and the skirt 5 are continuous with each other and disposed by facing on both sides of a pin boss axis C1 with the pin boss axis C1 between them. A horizontal section of the inner wall 10 is formed along a specific oval shape E.

[Problem to be Solved] A space from a skirt to a side wall is uniformly deformed in a wide range without a bias. [Solution] A piston 1 has two pin bosses 3 disposed so as to face each other at an interval, a side wall 4 disposed on both sides of the pin boss 3, and a skirt 5 provided continuously to the side wall 4, and a pin hole 3a into which a piston pin 1a can be inserted is formed in the pin boss 3. Inner walls 10 of the side wall 4 and the skirt 5 are continuous with each other and disposed by facing on both sides of a pin boss axis C1 with the pin boss axis C1 between them. A horizontal section of the inner wall 10 is formed along a specific oval shape E.

A piston for an internal combustion engine has box walls (18), which are each formed between skirt walls (12) and gudgeon pin bosses (10). At least one of the box walls (18) on a thrust side at least on the lower edge and at least on the inner side, starting from the gudgeon pin boss (10), in a first portion (20), runs largely straight and is inclined outwards, and then runs curved inwards, and then, in a second portion (16), runs largely straight and inclined inwards to the skirt wall (12).

A steel piston (1) for a combustion engine, having an upper part in which a ring section (7) with at least one ring groove (8) is arranged, wherein the upper part is adjoined by a lower part that has two opposing skirt wall sections (2), wherein the two skirt wall sections (2) are connected via two mutually opposite case walls (3), wherein a pin bore (4) surrounded by a piston boss (6) is provided in each case wall (3). In one example, there is at least one aperture (14) or at least one recess in the case wall (3) in the region between the piston boss (6) and the skirt wall section (2).

A power cylinder system for a reciprocating engine includes a piston configured to move within a cylinder of the reciprocating engine. The system also includes a groove extending circumferentially about the piston and configured to support a ring. An axially-facing surface of the groove has circumferential undulations at ambient temperatures that are configured to compensate for distortions to the groove caused by operation of the reciprocating engine.

A piston for use in an internal combustion engine having a pressure side and counterpressure side. The piston includes a piston skirt having skirt wall sections and box walls connecting the skirt wall sections. A spacing between the box walls on the pressure side is 35%-51% of the piston diameter and on the counterpressure side is 26%-39% of the piston diameter. Reduced angles of the extraction angle slopes on the pressure and counterpressure sides as well as larger free spaces are achieved which provides for lower piston mass and greater distribution of stresses in the box region of the piston.

A piston for use in an internal combustion engine having a pressure side and counterpressure side. The piston includes a piston skirt having skirt wall sections and box walls connecting the skirt wall sections. A spacing between the box walls on the pressure side is 35%-51% of the piston diameter and on the counterpressure side is 26%-39% of the piston diameter. Reduced angles of the extraction angle slopes on the pressure and counterpressure sides as well as larger free spaces are achieved which provides for lower piston mass and greater distribution of stresses in the box region of the piston.

A piston for an internal combustion engine may include two pin bosses configured to receive a gudgeon pin. The two pin bosses may respectively include a nadir pocket of at least two nadir pockets at =180 and extending outward from a piston axis. The at least two nadir pockets may have a respective length that is smaller than a length of a respective pin boss of the at least two pin bosses. The piston may also include a pin boss axis that is axially offset from the piston axis by 0.1-1.0 mm.