Piston seal device for a pneumatic cylinder

Abstract

A piston seal device of pneumatic cylinder which satisfies the required tightness of a seal as well as the required lubrication characteristics for a piston movement is disclosed. The piston seal device for maintining different pressures acting on each side of the piston of pneumatic cylinder comprises slide rings located on peripheries of both sides of piston, a seal ring located at the outer part of pressure room formed along the periphery of central part of the piston and operated by pneumatic pressure of the pressure room, and a solenoid valve which operates in selection modes to supply the pressurized air into the pressure room. Slide rings are located with a proper distance at the peripheries of both sides of a piston installed in a pneumatic cylinder and at the center of a piston an expansionable seal is applied. This seal is installed in the outer part of a pressure room formed peripherally along the piston and the pressure room is connected by pressure lines through which high pressure air is supplied by solenoid valves. The seal then is expanded by high pressure air to close the gap between the peripheral surface of piston and the cylinder inner wall.