Aeronautics and astronautics – Aircraft power plants – Mounting
Reexamination Certificate
2002-10-04
2004-07-06
Eldred, J. Woodrow (Department: 3644)
Aeronautics and astronautics
Aircraft power plants
Mounting
C060S039300, C248S554000
Reexamination Certificate
active
06758438
ABSTRACT:
BACKGROUND OF THE INVENTION
1. Field of Invention
The subject of this invention is an aircraft jet engine suspension.
2. Summary of the Prior Art
One common type of suspension comprises a pair of devices for attachment to the front and rear of the jet engine, each device fixed to a pylon of the aircraft, and a pair of roughly longitudinal intermediate link rods one of whose function is to spread the loads through the two attachment devices appropriately so that the attachment device at the rear transmits to its pylon the transverse and vertical forces and the moment about the longitudinal axis in addition to the thrust of the engine, which is exerted first and foremost on the front suspension.
This attachment device at the rear is thus subjected to many static and dynamic loads which lead to a high risk of breakage. If breakage occurs therein, other damage may ensue.
Fatigue cracks may thus appear on the master component of the attachment device, which runs along the pylon and toward which the longitudinal link rods and the lower links carrying the jet engine converge. This master component is generally fixed to the pylon by four screws arranged in a rectangle. If the fatigue progresses to the extent of breaking through the master component or of isolating some of the screws, then the forces are transmitted only by the other screws, and this is obviously highly unfavorable. The idea of splitting the master component into two parts between which the screws are distributed such that a crack stops at the split has been known.
Although this arrangement does stop the master component from breaking, it entails joining together the two portions which are separated by the split using bolts which greatly increase the weight of the suspension. A suspension of this kind is described in French Patent 2 680 353, where the master component is not only split but duplicated so that each of its parts alone is able to withstand the loads and its weight is then even greater.
The risk of fatigue breakage relates to the actual fixing screws. Certain precautions need to be taken such as limiting the tightening force applied to them on mounting, in order to reduce this risk.
SUMMARY OF THE INVENTION
The object of the invention is to substitute, for screws rendered unserviceable, at least one peg passing at least partially through the master component of the attachment device and the pylon which takes over in transmitting loads. The peg is produced in such a way as not to experience significant dynamic loads beforehand, and this sets aside the risk of it having broken through fatigue.
The invention relates specifically to a jet engine suspension comprising a device for attachment to a fixed structure, comprising a master component fixed to the structure, wherein the master component and the fixed structure are connected by a vertical peg exhibiting a central shoulder placed on the master component, an upper shoulder above a portion of the fixed structure, and a lower shoulder between which and the central shoulder the main component is compressed.
Advantageously, the lower shoulder and the upper shoulder are formed by nuts engaged on threaded end portions of the peg, a device for preventing the nut of the upper shoulder from rotating being added.
REFERENCES:
patent: 4603822 (1986-08-01), Chee
patent: 5873547 (1999-02-01), Dunstan
patent: 5921500 (1999-07-01), Ellis et al.
patent: 6341746 (2002-01-01), Pascal et al.
patent: 6494403 (2002-12-01), Jule et al.
patent: 6601796 (2003-08-01), Roszak
patent: 6607165 (2003-08-01), Manteiga
patent: 2003/0025033 (2003-02-01), Levert et al.
patent: 0 303 405 (1989-02-01), None
patent: 1 053 938 (2000-11-01), None
patent: 2 680 353 (1993-02-01), None
patent: 2 770 486 (1999-05-01), None
Brefort François
Huet Patrick
Pasquer Félix
Eldred J. Woodrow
Snecma Moteurs
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