초록 ▼

An adjustable labyrinth seal for a steam turbine wherein the packing rings may be displaced from a larger diameter position, affording a relatively larger shaft clearance, to a smaller diameter position, affording a relatively smaller shaft clearance. Steam conduits are provided in the turbine casin

An adjustable labyrinth seal for a steam turbine wherein the packing rings may be displaced from a larger diameter position, affording a relatively larger shaft clearance, to a smaller diameter position, affording a relatively smaller shaft clearance. Steam conduits are provided in the turbine casing communicating with the annular space between the individual packing rings and the grooves in which they are retained. The rings are provided with seals and are so configured as to maintain pressure- retaining contact with the sidewalls of the grooves. Steam, at a pressure in excess of the operating pressure of the individual seal, may be admitted to the annular space of the upstream ring to controllably effect the displacement thereof. Steam, at the turbine inlet pressure, is admitted to the annular spaces of the remaining rings to effect their displacement. In a further embodiment, one or more of the remaining rings may receive pressurized steam from an external source to control precisely the time at which they close.

대표청구항 ▼

An improved seal for a rotating machine for minimizing leakage between rotating and stationary components from a higher pressure upstream end of the machine to a lower pressure downstream end of the machine, said seal comprising: a plurality of segmented seal rings supported by, and at least partial

An improved seal for a rotating machine for minimizing leakage between rotating and stationary components from a higher pressure upstream end of the machine to a lower pressure downstream end of the machine, said seal comprising: a plurality of segmented seal rings supported by, and at least partially contained in, annular grooves formed in the stationary machine component to permit motion of each of said seal rings between a larger diameter position and a smaller diameter position corresponding respectively to larger and smaller clearances of said seal rings with regard to the rotating machine component, said grooves each being partially defined by a pair of opposing spaced apart shoulders on said stationary component which form an opening of said groove extending radially into a clearance area between said stationary component and said rotating component; each segment of each of said seal rings including an inner arcuate portion having a radially outwardly facing surface which is located opposite to a radially inward facing arcuate surface of said stationary component for limiting said larger clearance position by contact between said opposing surfaces, an outer ring portion disposed within one of said seal ring grooves for both axial and radial movement therein and having a pair of axial shoulders extending in opposite directions for making radial contact respectively with said pair of opposing spaced apart shoulders on said stationary component and thereby limiting said smaller clearance position, and a neck portion connected between said inner arcuate portion and said outer ring portion and extending between said opposing spaced apart shoulders, said neck portion having an axial thickness which is less than the distance between said opposing spaced apart shoulders to thereby axially locate said seal ring segment against one of said opposing spaced apart shoulders and provide a contact pressure seal at a downstream side of said neck portion; a compressed spring means biased against each segment of each of said seal rings for forcibly causing said seal rings to move to said larger clearance positions; first conduit means for admitting fluid from a first region of high pressure to said annular space between said stationary component and the segments of an upstream one of said seal rings, to controllably displace said segments to said smaller diameter positions; and second conduit means for admitting fluid from a second region of high pressure to the annular spaces between said stationary component and the segments of selected ones of said seal rings, other than said upstream seal ring, whereby said segments of said selected seal rings are displaced to said smaller diameter position.