APPARATO DI CONTROLLO DI GIOCO DI SOMMITA' DI PALETTE USANTE UN MECCANISMO POSIZIONATORE DI SEGMENTO DI FASCIA AZIONATO DA CAMME

摘要

A clearance control apparatus has a positioning mechanism for controlling clearance between rotor blade tips and a shroud segment of a gas turbine engine casing, and a rotatable lever for actuating the mechanism. The positioning mechanism is supported by a casing boss, coupled to the shroud segment, and actuatable for moving the shroud segment toward and away from the rotor blade tips to reach a position at which a desired clearance is established. The mechanism includes a shaft and a pair of cam elements. The shaft is mounted by the boss for radial movement toward and away from the rotor axis and coupled at its inner end to the shroud segment. An outer cam element is attached to the outer end of the shaft and spaced outwardly from the boss. An inner cam element is attached to an end of the lever mounted to the boss for rotational movement about a longitudinal axis of the shaft. The inner cam element is located between an outer end of the boss and the outer cam element and engaged with the outer cam element such that rotation of the inner cam element with rotation of the lever produces radial movement of the outer cam element and of the shaft and shroud segment therewith toward and away from the rotor blade tips.