Piston for an engine

A piston for an engine, comprising a piston body;

• wherein, a top land, a first compression ring groove, a second land, a second compression ring groove, a third land, an oil ring groove are disposed in turn on the periphery of the piston body from top to bottom;
• and more than one of annular expansion grooves are disposed on the periphery of the second land.

A piston for an engine, comprising a piston body;

• wherein, a top land, a first compression ring groove, a second land, a second compression ring groove, a third land, an oil ring groove are disposed in turn on the periphery of the piston body from top to bottom;
• at least one annular expansion groove is disposed on the periphery of the second land;
• at least one annular expansion groove is further disposed on the periphery of the third land.

A piston for an engine, comprising a piston body;

• wherein, a top land, a first compression ring groove, a second land, a second compression ring groove, a third land, an oil ring groove are disposed in turn on the periphery of the piston body from top to bottom;
• and at least one of annular expansion grooves are disposed on the periphery of the third land.