Back to results
US 4,901,629 AGranted
Sealing arrangement
AssigneeFramo Developments (UK) Limited
InventorFrank Mohn
Life of this patent
Estimating the term…
Loading patent…
Loading patent…
AssigneeFramo Developments (UK) Limited
InventorFrank Mohn
Estimating the term…
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.
An apparatus comprising a member which is reciprocable in a cavity, seal means operative between the member and the cavity walls, and drive means for producing reciprocal movement of the reciprocable member which, in use, is exposed at its opposite sides to fluids at respective first and second pressures, the first pressure being greater than the second pressure, the reciprocable member comprising a driving part, upon which the drive means act, and a driven part and the apparatus including means for generating during reciprocal movement of the member a fluid pressure in a chamber between the driving and driven parts, the pressure being greater than the first pressure and acting upon the seal means to provide an overpressure which prevents flow of the first fluid past the seal means and from one side of the reciprocal member to the other.
An apparatus comprising a member which is reciprocable in a cavity, seal means operative between the member and the cavity walls, and drive means for producing reciprocal movement of the reciprocable member which, in use, is exposed at its opposite sides to fluids at respective first and second pressures, the first pressure being greater than the second pressure, the reciprocable member comprising an annular driving part, upon which the drive means act, and a driven part having a stem portion, around which the annular part extends, and a head portion, between which and the cavity wall the said seal means are operative, the driving and driven parts having between them a chamber in which an overpressure is generated during reciprocal movement of the reciprocable member, the overpressure chamber being sealed from the second fluid by further seal means operative between the driving and driven parts and the apparatus including a passageway which communicates the overpressure chamber with the second fluid and contains a one-way valve allowing fluid flow into the pressure chamber during movement of the driving part relative to the driven part against the bias of resilient biassing means acting between the head portion of the driven member and the driving member.
An apparatus comprising a member which is reciprocable in a cavity, seal means operative between the member and the cavity walls, and drive means for producing reciprocal movement of the reciprocable member which, in use, is exposed at its opposite sides to fluids at respective first and second pressures, the first pressure being greater than the second pressure, the reciprocable member comprising a driving part, between which and the cavity wall the said seal means are operative and upon which the drive means act, and a driven part, the driven part being received in a well defined by an annular portion of the driving part and being joined to the driving part by a resilient diaphragm, a chamber, in which an overpressure is generated during reciprocal movement of the reciprocable member, being defined within the well and being sealed by further seal means from a portion of the well communicating with the second fluid and thereby exposing the driven part to the second fluid pressure, the apparatus including a passageway communicating the overpressure chamber with the second fluid and containing a one-way valve allowing fluid flow into the pressure chamber during movement of the driving part relative to the driven part against the bias of the resilient diaphragm.
Dependencies are inferred from the claim text.