Power plants – Reaction motor – With thrust direction modifying means
Reexamination Certificate
1999-09-02
2001-11-06
Freay, Charles G. (Department: 3746)
Power plants
Reaction motor
With thrust direction modifying means
Reexamination Certificate
active
06311478
ABSTRACT:
The present invention refers to an actuation mechanism for vectoring nozzles of variable geometry, for gas turbines used as propulsion systems in aviation.
The maneuverability of the airplanes is an essential factor. This maneuverability, which has been achieved up to date by aerodynamic forces, can substantially be improved by vectoring the thrust away from its conventional axial orientation
The vectoring of the thrust has been employed historically in rocket engines. In this applications vectoring is much simpler due to the fixed geometry of the nozzles.
Convergent divergent nozzles with variable geometry have been incorporated relatively recently on supersonic aircraft powered by jet engines or turbo fans.
For this type of nozzles the systems capable of vectoring thrust are not yet operational but rather on a stage of research and development. Those which are more advanced are of the two dimensional type, in which thrust vectoring is only achieved in one plane
It is of special interest to orientate the thrust in nozzles with axisymmetric geometry, because it allows to vector the thrust in any axial plane, and on those of special importance; the pitch and yaw planes.
There are several known mechanism for vectoring thrust in this type of nozzles, since it is possible to do it by different means, even though it is difficult to achieve enough simplicity.
Mechanism of the mentioned type are described in Spanish patent ES 9200369 and its equivalent American patent U.S. Pat. No. 5,329,763 and European EP 0557229 and also on the U.S. Pat. No. 5,613,636.
The patent ES 0557229 refers to a vectoring nozzle of variable geometry for gas turbines, consisting of a convergent section, followed in the thrust direction by a divergent section, both made up of master and slave petals. The convergent section defines a variable geometry throat, and the divergent section is of variable geometry to vector the thrust. The nozzle includes devices to vary the throat area and devices to vary the thrust orientation, being both devices made up a unique mechanism consisting of three annular rings, concentric between them and with the engine axis, and by a number of linear actuators. Each two consecutive parts from the three annular rings are joint in an arrangement of three elements with diametric axis perpendicular between them as in a cardan or universal joint. The external annular ring can be a single part or two halves joined by a cylindrical joint with its axis coincident with the joint between external and intermediate rings.
With this arrangement a nozzle capable of fulfilling the following functions is obtained: a) simultaneous axisymmetric variation, according to a fixed ratio, of the convergent section throat area and the divergent section exit area; b) simultaneous variation of all the geometry of the divergent section exit area, independently of the throat area; and c) asymmetric orientation of thrust.
The Spanish patent number 9401114 refers to a nozzle of the described type that can achieve a fourth function that adds to the already mentioned, consisting of the independent variation of the divergent section exit area independently of the convergent section throat area. This is achieved by the special arrangement of the external ring, consisting of two or more sectors joined between them, together with an actuation mechanism that allows, by the independent rotation of one of the ring segments, the asymmetric correction of the divergent section exit area during a vectorization, while the remaining sections of the ring remain static.
In both cases the external ring is related to the fixed structure by a guiding mechanism. This arrangement allows the external ring to withstand the tangential forces that result from vectoring the thrust, and transmit them to the fixed structure.
The present invention objective is to define an arrangement of a thrust vectoring nozzle of variable geometry, of the mentioned type, with a simplified and reduced number of elements for transmitting the tangential forces that act on the external ring as a result of divergent section vectoring, onto the engine structure.
For this purpose the invention summarizes an alternative guiding system between the annular rings that make up the actuation mechanism of the convergent section throat area and the geometry of the divergent section.
With more detail, the invention proposes a guiding system between gas turbine propulsion variable geometry vectoring nozzle annular rings, capable of withstanding the tangential loads on the outer ring that result from vectoring, and transmit them to the internal ring, without the need of a guiding system between the external ring and the fixed structure.
The mechanism of the invention is characterized because it includes elements capable of guiding the relative rotation between connecting rings, allowing the transmission of tangential loads acting on the external ring as a result of vectoring of thrust, onto the internal ring, avoiding the need of a direct joint between the external ring and the nozzle structure.
The mentioned devices, by which the relative movement between each two consecutive rings is conducted, consists in at least one roller or sliding track located in one of the rings and of a roller or sledge mounted on the other, being the roller or sledge elements positioned against the track in which it rolls or slides. The tract is orientated circunferencially around the rotation axis between the two rings being considered.
Preferably each couple of consecutive rings is related by two tracks and an equal number of associated sledges or rollers. The two tracks are preferably located at opposite diametral positions and preferably at opposite sides of the plane perpendicular to the axis of rotation.
REFERENCES:
patent: 5329763 (1994-07-01), Mendia et al.
patent: 5613636 (1997-03-01), Zubillaga et al.
Elorriaga Vicario Javier
Villanueva Salazar Miguel
Darby & Darby
Freay Charles G.
Industria de Turbo, S.A.
Rodriguez William H
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