Positive clearance radial face seals

A positive clearance radial face seal of which at least one of its two opposed sealing faces comprises a pressure-deflectable elastic or elastically-loaded element which deflects, in steady state operating conditions, to provide a clearance between the sealing faces which converges in the radial direction to a minimum clearance towards the downstream zone of the seal, the deflection changing with variations in the operating conditions in a manner tending to restore the steady state clearance, said pressure-deflectable element being an annular member having rigid radially inner and radially outer annular portions supporting an intermediate annular elastic portion, the other face of said element, which is on the other side from and faces oppositely to the sealing face, being acted upon over at least part of the upstream one of said rigid annular portions by the upstream fluid pressure of the seal and being acted upon over any remaining part of said other face of said one annular portion and over said intermediate portion by the downstream fluid pressure of the seal, and the pressure-deflectable element being supported against axial movement at said other annular portion, and the net load resulting from said fluid pressures and from the mean leakage fluid pressure being opposed by the forces generated by the deflection of the element, whereby to ensure that the clearance between the sealing faces converges in the radial direction towards the downstream zone of the seal.

A positive clearance radial face seal comprising a pair of relatively rotatable parts, a first sealing member constrained against rotation with respect to one of said parts, a second sealing member constrained against rotation with respect to the other of said parts, said first and second sealing members having co-operating opposed sealing faces, which resist fluid flow between said sealing faces from a high pressure region to a low pressure region, at least one of said sealing faces comprising a pressure-deflectable elastic or elastically-loaded element which in its unstressed condition provides a sealing face which is substantially planar in the radial direction and which, in steady state operating conditions, deflects to provide a clearance between said sealing faces which converges in the downstream radial direction to a minimum clearance at an annular zone between the downstream ends of the co-operating sealing faces, said pressure-deflectable element changing its deflection with variations in the operating conditions, in the sense of increasing the convergence in the downstream direction with increase of the pressure difference across the sealing faces and decreasing said convergence with decrease of said pressure difference, thereby tending to restore said minimum clearance to its steady state value, and including resilient pre-load means opposing deflection of the upstream end of the pressure-deflectable element.