Trunnion-to-disk connection for an open fan configuration aircraft powerplant
A trunnion-to-disk connection for use on an open fan configuration of a gas turbine engine may include an integral trunnion and blade spar inserted through a trunnion aperture of a fan disk and supported by top bearing and a bottom bearing. A cavity can be provided between a trunnion of the integral trunnion and blade spar and the fan disk, as well as between the top bearing and bottom bearing. Pressurized hydraulic fluid can be supplied to the cavity to urge the integral trunnion and blade spar in a direction to preload the bearings. Prior to pressurization, and prior to installation of the bottom bearing, the trunnion can be inserted into a trunnion aperture of the fan disk such that an end of the trunnion extends past the fan disk to provide sufficient space to insert the bottom bearing from within the open interior of the fan disk.
1. A trunnion-to-disk connection for an open fan engine, the trunnion-to-disk connection comprising:
a fan disk having an annular shape defined about a longitudinal axis, the fan disk defining a plurality of trunnion apertures and an inner surface, the inner surface defining a minimum radius from the longitudinal axis at a location aligned with the plurality of trunnion apertures, the plurality of trunnion apertures including a first aperture;
a plurality of fan blades including a first fan blade having a central blade axis, the first fan blade further including an integral trunnion and blade spar positioned at least partially in the first aperture of the fan disk, a trunnion of the integral trunnion and blade spar including a first trunnion end including a foot and a second trunnion end opposite the first trunnion end, the foot having a bearing contact surface; and
a bottom bearing captured between the bearing contact surface of the foot of the trunnion and the inner surface of the fan disk, the bearing contact surface defining a radius from the longitudinal axis less than the minimum radius of the inner surface of the fan disk;
wherein an access space is defined by the inner surface of the fan disk and the foot of the integral trunnion and blade spar, the access space configured to facilitate loading of the bottom bearing.
2. The trunnion-to-disk connection of claim 1 , wherein the bottom bearing includes a rolling element captured between an upper race and a lower race, wherein the lower race is a split race.
3. The trunnion-to-disk connection of claim 1 , wherein each of the plurality of trunnion apertures includes a central aperture axis oriented coincident with the central blade axis.
4. The trunnion-to-disk connection of claim 1 , wherein each of the plurality of trunnion apertures includes a central aperture axis, and wherein the integral trunnion and blade spar is structured to rotate about the central aperture axis to provide variable pitch to each of the plurality of fan blades.
5. The trunnion-to-disk connection of claim 4 , wherein the foot extends transverse to the central aperture axis and away from the trunnion.
6. The trunnion-to-disk connection of claim 1 , wherein the fan disk includes an inner abutment surface for bearing a load of at least one of the plurality of fan blades, which further includes a spanner nut located at the second trunnion end of the integral trunnion and blade, and wherein tightening of the spanner nut urges the foot to capture the bottom bearing between the foot and the inner abutment surface.
7. The trunnion-to-disk connection of claim 1 , further comprising a top bearing and a foam insert, the foam insert positioned between the bottom bearing and the top bearing.
8. The trunnion-to-disk connection of claim 1 , further comprising a top bearing, wherein a cavity is defined between the fan disk and the trunnion of the integral trunnion and blade, the cavity also defined between the top bearing and the bottom bearing.
9. The trunnion-to-disk connection of claim 8 , wherein a cavity is defined between the fan disk and the trunnion of the integral trunnion and blade, and wherein the cavity is in lubricant isolation from another cavity defined between another integral trunnion and blade spar and the fan disk.
10. The trunnion-to-disk connection of claim 8 , wherein each of the plurality of trunnion apertures includes a central aperture axis oriented to extend radially toward the longitudinal axis of the fan disk, and wherein the trunnion-to-disk connection further includes a grease port in fluid communication with the cavity, wherein the grease port is structured to deliver pressurized grease to the cavity to aid in forcing movement of the integral trunnion and blade spar along the central aperture axis.
11. The trunnion-to-disk connection of claim 1 , wherein the fan disk is coupled to a low pressure shaft of a gas turbine engine, and which further includes the gas turbine engine.