Patent ID: 7931003

Claim:
A reciprocating engine comprises: a first piston ring disposed adjacent to a top surface of a piston defining a combustion chamber; a second piston ring, said first piston ring being interposed between said second piston ring and the top surface of said piston; an annular gas chamber defined by said first piston ring and said second piston ring; and one or a plurality of communicating passages for allowing said annular gas chamber and said combustion chamber to communicate with each other, said first piston ring being inclined with respect to a reciprocating direction of said piston so as to dispose a portion on a thrust side of the first piston ring in closer proximity to the top surface of said piston in the reciprocating direction than a portion on an anti-thrust side of the first piston ring, said second piston ring being inclined in a direction which is opposite to an inclined direction of said first piston ring with respect to the reciprocating direction of said piston, wherein said first piston ring and said second piston ring are located further away from each other on the thrust side than on the anti-thrust side.