Patent ID: 9423028
Filing Date: 2016-08-23
CPC Classification: F16J

Claim Text:
1. A piston assembly, comprising: a piston body including at least two lands spaced axially from one another by a ring groove and one of said lands presenting a chamfer at an outer surface thereof; an intermediate piston ring disposed in said ring groove between said lands, said piston ring extending through an arcuate shape between opposite end faces and having an upper surface and a lower surface and an outer oil scraping edge which is axially located between said upper and lower surfaces; and said intermediate piston ring including a radially inwardly facing surface and a radially outwardly facing surface and wherein said piston body includes at least one undercut between said outer scraping edge and said lower surface that extends radially the full distance between said inwardly and outwardly facing surfaces for allowing combustion gasses to flow past said piston ring through said chamfer when said piston assembly is moving in only one axial direction with said piston ring being seated against said at least one land with said chamfer.