Ringless piston

Claim 1

A piston and cylinder assembly of the type wherein a piston is reciprocally mounted within a cylinder to produce variant pressure conditions on opposite sides of the piston during reciprocation thereof, the improvement comprising a cylinder and a piston reciprocally mounted therein, to develop a pressurized space in said cylinder, said piston having an outside wall surfAce providing a normal running clearance with the opposed wall of said cylinder and with a clearance space between the piston wall surface and the opposed cylinder wall, said piston having an extended skirt-like flange on the end thereof opposed to a closed end of the cylinder, said flange having a continuous circular wall, the normal outside diameter of said skirt-like flange being such as to provide a normal running clearance with a space between the wall of the flange and the opposed wall of the cylinder when the piston is positioned within the cylinder in an unpressurized condition, said skirt-like flange having a radial width and an axial length such, with relation to the outside diameter of said piston and flange, with relation to the particular material of which the piston and skirt-like flange are made, and with relation to the normal operating pressure developed within the cylinder against the end of the piston carrying said skirt-like flange, that said skirt-like flange is expanded outwardly because of the hoop-like bursting stresses developed therein during normal operating pressures such that the outer wall of said skirt-like flange is forced into wiping and sealing contact with the opposed wall of the cylinder during reciprocation of said piston, said piston and cylinder being further characterized by the absence of sealing rings or expansion rings, the wall thickness of said flange being such that the stresses developed on said flange are within the elastic limits of the material of the flange whereby the flange resiliently recedes toward its original condition after removal of said pressurized condition.