Power plants – Reaction motor – With destruction sensing and preventing means
Reexamination Certificate
1998-12-09
2001-06-05
Kim, Ted (Department: 3746)
Power plants
Reaction motor
With destruction sensing and preventing means
C060S039091, C060S039300
Reexamination Certificate
active
06240719
ABSTRACT:
BACKGROUND OF THE INVENTION
This invention relates generally to fan support systems and, more particularly, to a fan decoupler system for fan imbalances on a gas turbine engine.
Gas turbine engines include a fan section, a compressor section, a combustor section, and a turbine section. A shaft extends axially through the turbine section and rotates a rotor. The rotor includes multiple stages of disks. Each disk carries circumferentially spaced apart blades that extend radially across a gas flow path. Rotor support structure typically includes a support cone extending from a bearing often referred to as the number one bearing.
During a large birdstrike, fan bladeout, or other large fan imbalance event, structural loads carried throughout the engine carcass, flanges, engine frame, and mounts, can be quite large. Typically, these loads are compensated for by stiffening the system and providing a fan critical speed significantly above the operating speeds of the engine. As a result, the structural loads are reduced, and the entire structure is fabricated to account for the reduced loads. Such compensation for a potential fan imbalance event, however, results in a structure which may be heavier than desired.
Accordingly, it would be desirable to provide a support structure system that adequately handles a large fan imbalance event, without adding significant weight to the gas turbine engine. Additionally, it would be desirable for the support structure system to be cost effective.
SUMMARY OF THE INVENTION
These and other objects may be attained by a support structure for a gas turbine engine that includes a member having a reduced failure point. In accordance with one embodiment, the turbine engine includes a support cone having a support arm. The support arm extends between the low pressure shaft and the rotor, and includes a fuse having a failure point below the failure point of the remaining portion of the support cone. The fuse includes a bolt that connects two portions of the support arm. The bolt extends through a segmented spacer positioned between the two sections. The bolt has a failure point selected to coincide with a predetermined imbalance load.
The high pressure shaft includes a stub shaft that axially and radially supports the low pressure shaft after failure of the bolt. An axial opening extends between a portion of the low pressure shaft and the stub shaft. The opening permits movement of the low pressure shaft toward the stub shaft after the bolt has failed. Movement of the low pressure shaft towards the stub shaft positions the two shafts in contact with each other and causes both shafts to decelerate to a common speed. The low pressure shaft and the stub shaft continue to rotate at the same speed due, at least in part, to the friction between the two shafts.
A radial opening exists between the stub shaft and the low pressure shaft prior to bolt failure. The radial opening allows free radial deflection of the low pressure rotor system after fuse failure. A radial opening between a high pressure rotor disk and the low pressure shaft permits the bore at the tip of the rotor disk to contact the low pressure shaft after bolt failure. The rotation of the high pressure rotor is slowed due to contact of the low pressure shaft with the stub shaft.
The support cone including the fuse provides a failure point in the structural load path which “softens” the structural system during a large imbalance event to allow the low pressure shaft to move axially and radially with respect to the high pressure shaft. This failure point reduces the overall peak loads carried by the structural system. The structural system can thus be lighter and less costly than previous structural systems that were stiffened to handle large imbalance loads.
REFERENCES:
patent: 4313712 (1982-02-01), Briggs
patent: 4375906 (1983-03-01), Roberts et al.
patent: 4827712 (1989-05-01), Coplin
patent: 5433584 (1995-07-01), Amin et al.
patent: 5974782 (1999-11-01), Gerez
patent: 6073439 (2000-06-01), Beaven et al.
patent: 6098399 (2000-08-01), Richards et al.
patent: 6109022 (2000-08-01), Allen et al.
patent: 2192233 (1988-04-01), None
Glynn Christopher C.
Tseng Wu-Yang
Vondrell Randy M.
General Electric Company
Herkamp Nathan D.
Hess Andrew C.
Kim Ted
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