Blade tip clearance control apparatus with shroud segment position adjustment by unison ring movement

摘要

A clearnace control apparatus has a plurality of positioning mechanisms and an annular unison ring for controlling the clearance between the rotor blade tips and shroud segments of a gas turbine engine casing. The positioning mechanisms are supported by circumferentially-spaced casing bosses, connected to the shroud, and actuatable by the unison ring for moving radially toward and away from the rotor blade tips. As the positioning mechanisms are moved radially, the shroud segments move therewith toward and away from the rotor axis to positioned between inner and outer positions which define minimum and maximum clearances between the shroud segments and rotor blade tips. The unison ring has circumferentially spaced slots defined therethrough each extending in a transverse inclined relation to the respective directions of movement of the unison ring and positioning mechanisms and having spaced opposite ends defining first and second angularly displaced limit positions of the unison ring. The positioning mechanisms are coupled to the unison ring by pins which extend through the respective inclined slots.