Rolls-royce Corporation

John W Allen

Kenneth Franklin Udall

James Kell

Dragos Aurelian Axinte

David Michael Beaven

Martyn Richards

Christopher Freeman

Peter G Farrar

Stephen H Watson

Alan R Maquire

Mark Raffles

Adam Rushworth

A ducted fan gas turbine engine comprises a fan mounted on a first shaft and a compressor mounted on a second shaft The shafts are coaxial both with each other and with said engine longitudinal axis The shafts are mounted in roller bearings The first bearing carrying the upstream part of the first shaft and the second bearing carrying the upstream part of the second shaft. Both bearings are attached to a structure which comprises an axial sleeve and a front frustoconical portion and a rear radially stiff but axially flexible frustoconical portion and is attached to the engine casing The front frustoconical portion is frangibly attached to the front part of the axial sleeve In the event of damage to the fan the frangible connection breaks and the first shaft is allowed to orbit about the engine longitudinal axis The rear member is swashingly non-linear flexible and accommodates the out of balance radial loads transferred to it as couples during such an incident.

Ducted fan gas turbine engine with frangible connection

A vibration damper comprises a bearing located between two rotatable shafts and an axially extending oil entry surface positioned radially inwardly of the radial outer surface of the bearing outer race and axially adjacent one end of the bearing. The outer surface of the bearing outer race forms a clearance between itself and the bearing housing for the ingress of a film of oil directed from the oil entry surface. A weir is positioned at the axially opposite end of said bearing and radially inward of the bearing outer race and oil entry surface such that in use the radial height difference between oil entry surface and weir provides a pumping force and supplies a film of oil between the bearing outer race and its casing.

Bearing damper

A ducted fan gas turbine engine (10) is provided with a fan (12) which is carried by a shaft (16). A frangible support member (27) maintains a coaxial relationship between the shaft (16) and the longitudinal axis (15) of the engine (10). In the event of severe damage to the fan (12), the frangible member (27) fractures, allowing the shaft (16) carrying the fan (12) to orbit about the engine longitudinal axis (15). A resilient support member (33,45) exerts a radially inward restoration force on the shaft (16) carrying the fan (12) to reduce vibration.

Turbofan with frangible rotor support

A ducted fan gas turbine has a fan shaft which is supported at its upstream end by a bearing. In the event of damage to the engine's fan, frangible bolts fracture to permit radial movement of the shaft. That movement is limited by the sequential engagement of the outer race of the bearing with first and second movement limiting portions on fixed structure of the engine. This alters the natural frequency of vibration of the fan, so permitting the fan to windmill without excessive vibration.

Ducted fan gas turbine engine

A ducted fan gas turbine engine is provided with a fan which is carried by a shaft. A frangible fuse ring maintains the shaft carrying the fan coaxial with the engine longitudinal axis. In the event of severe fan damage, the fuse ring (28) fractures and the fan shaft orbits about the engine longitudinal axis. A pair of threaded members (39, 41), one of which is of generally frusto-conical configuration, cooperate as a result of the orbiting motion to restore the coaxial relationship between the fan shaft and the engine longitudinal axis.

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Burton on Trent, United Kingdom

John W Allen