Chamfered attachment for a bladed rotor

#This application includes subject matter in common with co-pending applications entitled “Axial Retention System and Components thereof for a Bladed Rotor”, docket number EH-10555 and “Bladed Rotor with a Tiered Blade to Hub Interface”, docket number EH-10560, both filed concurrently herewith, all three applications being assigned to or under obligation of assignment to United Technologies Corporation.

#This invention relates to an axial retention system and components thereof for a bladed rotor, particularly a fan rotor of a gas turbine engine.

#A fan rotor of the type used in an aircraft gas turbine engine includes a hub capable of rotating about a rotational axis and an array of blades extending radially from the hub. The hub includes a series of circumferentially distributed peripheral slots. Each slot extends in an axial or predominantly axial direction and has a pair of overhanging lugs, each with an inwardly facing bearing surface. When viewed in the radial direction, each slot may be linear, with the slot centerline oriented either parallel or oblique to the rotational axis, or may have a curved centerline and a corresponding curved shape. Each slot is typically open at either the forward end of the hub, the aft end of the hub, or both to facilitate installation and removal of the blades.

#FIG. 1 is a cross sectional side elevation view of an aircraft gas turbine engine fan rotor showing the principal features of the inventive axial retention system, the plane of the view being circumferentially offset from a blade receiving slot in the rotor hub.

#FIG. 2 is an exploded perspective view of the principal elements of the inventive axial retention system.

#FIG. 3 is an enlarged view similar to that of FIG. 1, but taken in the plane of a hub slot, showing the inventive axial retention system in an early state of assembly.

#Referring principally to FIGS. 1 and 2, a fan rotor of an aircraft gas turbine engine includes a hub 12 rotatable about a rotational axis 14. The hub includes a series of circumferentially distributed peripheral slots 16. The illustrated slots, when viewed by an observer looking radially toward the axis, have a curved centerline 18 and a correspondingly curved profile. The centerline has a radius of curvature R. Alternatively, the slots may be linear slots having a linear centerline oriented parallel or oblique to the rotational axis. A slot opening 22 at the forward end of the hub, the aft end of the hub or both accommodates installation or removal of fan blades, described below, in the axial direction. As used throughout this specification, the term “axial” refers not only to a direction strictly parallel to the rotational axis but also to directions somewhat non-parallel to the axis, such as the slotwise direction defined by a curved or linear slot. As seen best in FIG. 9, each slot is bounded radially by a floor 26 and a pair of overhanging lugs 28 with inwardly facing bearing surfaces 30.

#Referring additionally to FIG. 3, the hub comprises a main body 32 with radially inner and outer bayonet hooks, 34, 36 projecting axially from the main body. The inner and outer hooks are circumferentially offset from each other and cooperate with the main body 32 of the hub to define an annulus 38.

#The fan rotor also includes an array of fan blades such as representative blade 40. Each fan blade comprises an attachment 44, a platform 46 and an airfoil 48, although some rotors employ platforms non-integral with the blades. The attachment has a base surface 50. The attachment is curved or linear to match the shape of the hub slots. In an assembled rotor, and as seen most clearly in FIG. 9, the attachment 44 of each blade occupies one of the hub slots. Bearing surfaces 52 on the flanks 54 of each attachment cooperate with the lug bearing surfaces 30 to radially trap the blade.