Sealing arrangement

US4901629A · kind A · utility

Assignee

• Framo Developments (UK) Limited · GB

Inventor

• Frank Mohn · London, GB

Key dates

• Filing date: Oct 31, 1988
• Grant date: Feb 20, 1990
• Expiry date: Oct 31, 2008

Classification

• Technology area (CPC F): Mechanical Engineering; Lighting; Heating
• CPC primary: F16J15/406
• WIPO field: Mechanical elements
• WIPO sector: Mechanical engineering

Abstract

FIG. 1 shows a sealing arrangement which includes a mushroom-shaped piston is driven to reciprocate in a cylinder by an annular driving part extending around its stem. The driving part forms the "rotor" of a linear electric motor, the "stator" of which is provided by the cylinder. The ends of the piston are exposed to respective greater and lesser pressures. During movement of the driving member relative to the piston against the bias of a spring, fluid flow through a passage containing a one-way valve generates an overpressure in a chamber to which a seal between the piston head and the cylinder is exposed and thus prevents leakage of fluid around the seal. FIG. 2 shows a modification in which the piston has a central well containing a plunger biassed by a diaphragm. Here the overpressure is generated in the well and a passage exposes a seal to the overpressure to prevent leakage around the piston.