Aeronautics and astronautics – Aircraft – heavier-than-air – Helicopter or auto-rotating wing sustained – i.e. – gyroplanes
Reexamination Certificate
1999-07-09
2001-04-17
Poon, Peter M. (Department: 3643)
Aeronautics and astronautics
Aircraft, heavier-than-air
Helicopter or auto-rotating wing sustained, i.e., gyroplanes
C244S017230, C416S039000, C416S095000
Reexamination Certificate
active
06216979
ABSTRACT:
The invention relates to improvements made to systems in accordance with EP 0 754 623 for the electrical connection between at least one electrical power supply conductor and an electrical de-icing device of a rotor blade of a rotor aircraft, of the type including:
a hub, rotating integrally with a rotor mast around an axis of rotation of the rotor, and
at least two blades, each of which is connected to the hub by means of a connection part substantially radial relative to the axis of rotation and itself connected to the hub by retaining and articulation means.
As in EP 0 745 623, by electrical de-icing device must be understood any de-icing or anti-icing device requiring, for its operation, actuation or control, an electrical power supply.
The connection system of the invention is of the type known via EP 0 754 623 and including at least one cable connecting to at least one electrical conductor and connecting said power supply conductor carried by the hub to at least one electrical conductor of said de-icing device carried by the blade, the connection cable including a first section, one first end of which, in the internal radial position, is connected to said power supply conductor of the hub by a first connector mounted on the hub, and the second end of which is connected to a first end of a second section of said connection cable, said second section including a first aerial brace, in the shape of a flattened half-loop, and its second end being connected to said de-icing conductor of said blade by a second connector, installed on the blade, at least said first brace having a non shielded structure and having an elongated part of flattened substantially rectangular transverse section, the largest dimension of which is substantially perpendicular to the axis of rotation, and a concavity turned substantially towards said articulation and retaining means, said first brace being able to bend and to twist to accommodate angular pitch, lag and flapping movements of the blade and of its connection part relative to the hub.
Although the non-shielded structure, the flattened substantially rectangular transverse section and the arrangement of the first brace allow it to bend and twist to accommodate the aforementioned angular movements, the first brace nonetheless withstands not insignificant stresses, by virtue, in particular, of the rigid connection of the second end of the second cable section on the connection part, particularly by means of a plate supporting head lock-washers of connecting bolted pins of an internal radial armature of the retaining and articulation means in an internal radial clevis of the connection part, in a particular embodiment described in EP 0 754 623. The drawback of such a rigid connection is that it transmits to the first aerial brace stresses linked in particular to the angular pitch movements of the connection part and of the blade, to the frequency of blade pitch control, and therefore to the twisting distortions of the second cable section with this frequency.
The object of the invention is to propose a connection system of the type known via EP 0 754 623, and for which the mechanical and electrical resistance of the connection cable is further improved, in particular with regard to its first aerial brace, by fittings ensuring an attenuation of mechanical stresses at least of the second connection cable section, when the rotor rotates.
Another object of the invention is to propose such a system reducing also the stresses and/or movements of the connection cable in its section connecting the connection part to the blade root when these two components are separate, and, in a general way, being better suited to the different practical demands than known embodiments, particularly via EP 0 754 623.
To this end, the connection system according to the invention is characterised in that said second end of said second section is connected to said connection part by a first connection which is articulated at least by pivoting around an axis substantially parallel to the longitudinal pitch change axis of said connection part and said blade.
This pivoting articulated connection avoids or at least reduces the distortions of the connection cable from the pitch movements of the connection part and of the blade, from the controlling frequency of the blades, which gives the connection cable a longer life.
According to an advantageously straightforward embodiment, this first articulated connection includes a pivot pin, secured to one of the two components constituted by a fixing plate on said connection part and a support of said second end of said second cable section, said pivot pin extending in a substantially radial plane passing through the axis of rotation and the pitch axis and being pivoting mounted, preferably with the interposition of a selflubricating bearing, in a sleeve secured to the other of said two components constituted by said fixing plate and said support.
However, in an embodiment which is advantageous in that it also allows the second cable section at least partial relief from the stresses occasioned by lagging and flapping motions of the connection part and of the blade, the first articulated connection includes a ball joint connection between a support of said second end of said second cable section and a fixing plate on said connection part, and this ball joint is to advantage centered in a substantially radial plane passing through the rotation and pitch axes, and is retained around a pivot pin substantially parallel to said pitch axis of said connection part and of said blade, so as to allow this articulated connection to be acted upon relatively symmetrically forwards and backwards, during the different angular movements of the connection part and the blade.
Additionally, when the second end of the second cable section is connected to the second connector by being connected, as is known via EP 0 754 623, to a first end of a third connection cable section, this third section extending substantially radially on the connection part by being fixed to the latter by at least said first connection and a second connection, respectively near its first and second ends, in respectively internal and external radial positions, and when said third section is connected by its second end to said second connector, it is advantageous for the support of said first articulated connection to be a cable connector support between said second end of said second cable section and said first end of said third cable section. These two contiguous ends of consecutive sections of the connection cable are thus actuated by the same pivoting, ball joint, movement relative to the connection part and to the blade, when these latter perform their angular movements on a rotating rotor, which causes less stress on the corresponding cable connector.
For a rotor on which each connection part is distinct from the corresponding blade root and comprises an external radial part arranged, directly or indirectly, in an external clevis in which said blade root is retained, and pivoting mounted around a folding pin of said blade relative to said connection part, and on which additionally the connection between said second cable section and said second connector is provided, as known via EP 0 754 523, by means of a fourth cable section, including a second aerial brace extending from said connection part to the blade, and an end part of which is connected to said second connector, it is additionally advantageous for a part of said second aerial brace to be retained in at least one retaining part mounted in the substantially axial extension of said folding pin.
This technical measure provides the following advantages: on a manual blade folding rotor, on which the external radial part of each connection part is directly arranged as an external clevis, in which the corresponding blade root is retained by two pins substantially parallel to each other, and one of which is removable to allow manual blade folding relative to the connection part by pivoting around the other pin, it is no longer
Faure Thierry
Scala Vincent
Eurocopter
Jakel Kevin
Piper Marbury Rudnick & Wolfe
Poon Peter M.
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