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 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 compressor (20) has a case (22) and a crankshaft (38). The case has a number of cylinders (30-32). For each of the cylinders, the compressor includes a piston (34) mounted for reciprocal movement at least partially within the cylinder. A connecting rod (36) couples each piston to the crankshaft. A pin (44) couples each connecting rod to the associated piston. Each pin has first (52) and second (53) end portions mounted to first (56) and second (57) receiving portions of the associated piston and a central portion (48) engaging the associated connecting rod. For each of the pistons a pair of first and second at least partially non-metallic plugs have respective stems received in the pin first and second end portions and respective heads facing a wall surface of the associated cylinder.

A compressor (20) has a case (22) and a crankshaft (38). The case has a number of cylinders (30-32). For each of the cylinders, the compressor includes a piston (34) mounted for reciprocal movement at least partially within the cylinder. A connecting rod (36) couples each piston to the crankshaft. A pin (44) couples each connecting rod to the associated piston. Each pin has first (52) and second (53) end portions mounted to first (56) and second (57) receiving portions of the associated piston and a central portion (48) engaging the associated connecting rod. For each of the pistons a pair of first and second at least partially non-metallic plugs have respective stems received in the pin first and second end portions and respective heads facing a wall surface of the associated cylinder.

A compressor (20) has a case (22) and a crankshaft (38). The case has a number of cylinders (30-32). For each of the cylinders, the compressor includes a piston (34) mounted for reciprocal movement at least partially within the cylinder. A connecting rod (36) couples each piston to the crankshaft. A pin (44) couples each connecting rod to the associated piston. Each pin has first (52) and second (53) end portions mounted to first (56) and second (57) receiving portions of the associated piston and a central portion (48) engaging the associated connecting rod. For each of the pistons a pair of first and second at least partially non-metallic plugs have respective stems received in the pin first and second end portions and respective heads facing a wall surface of the associated cylinder.

A compressor (20) has a case (22) and a crankshaft (38). The case has a number of cylinders (30-32). For each of the cylinders, the compressor includes a piston (34) mounted for reciprocal movement at least partially within the cylinder. A connecting rod (36) couples each piston to the crankshaft. A pin (44) couples each connecting rod to the associated piston. Each pin has first (52) and second (53) end portions mounted to first (56) and second (57) receiving portions of the associated piston and a central portion (48) engaging the associated connecting rod. For each of the pistons a pair of first and second at least partially non-metallic plugs have respective stems received in the pin first and second end portions and respective heads facing a wall surface of the associated cylinder.

A piston may include a first center bore and a second center bore configured to receive a piston pin. The first center bore and the second center bore may have different diameters. An axis of the first center bore may extend parallel to an axis of the second center bore.

A piston may include a first center bore and a second center bore configured to receive a piston pin. The first center bore and the second center bore may have different diameters. An axis of the first center bore may extend parallel to an axis of the second center bore.

A steel piston for coupling to a connecting rod and wrist pin is provided. The piston includes a body with an upper crown presenting a combustion surface for exposure to a combustion chamber. The upper crown presents an undercrown surface which is openly exposed as viewed from an underside of the piston and not bounded by a cooling gallery. The body includes a ring belt and pin bosses depending from the ring belt and presenting a pin bore for receiving the wrist pin. The body also includes ribs disposed along the undercrown surface. The body includes a ratio of compression height to outer diameter (CH/D) ranging from 34.8% to 42.0%. The piston also includes a low heat transfer coating on the combustion surface, and the low heat transfer coating has a thermal conductivity of about 0.20 to 0.80 W/m.Math.K.

A steel piston for coupling to a connecting rod and wrist pin is provided. The piston includes a body with an upper crown presenting a combustion surface for exposure to a combustion chamber. The upper crown presents an undercrown surface which is openly exposed as viewed from an underside of the piston and not bounded by a cooling gallery. The body includes a ring belt and pin bosses depending from the ring belt and presenting a pin bore for receiving the wrist pin. The body also includes ribs disposed along the undercrown surface. The body includes a ratio of compression height to outer diameter (CH/D) ranging from 34.8% to 42.0%. The piston also includes a low heat transfer coating on the combustion surface, and the low heat transfer coating has a thermal conductivity of about 0.20 to 0.80 W/m.Math.K.