Fluid reaction surfaces (i.e. – impellers) – With heating – cooling or thermal insulation means
Reexamination Certificate
2001-11-19
2002-11-19
Verdier, Christopher (Department: 3745)
Fluid reaction surfaces (i.e., impellers)
With heating, cooling or thermal insulation means
C416S143000, C244S13400A
Reexamination Certificate
active
06481965
ABSTRACT:
The invention relates to a rotary-wing aircraft rotor whose blades are, at least for some of them, foldable and equipped with electrical equipment, for example a de-icing or anti-icing equipment, requiring the routing of electrical energy or signals between the blades and an electrical collector placed at the centre of the hub of the rotor. This routing of electrical energy or signals is provided by an electrical connection installation, essentially comprising an electrical harness comprising, for each blade, at least one electrical connecting cable, tied to a member for linking the corresponding blade to the hub of the rotor, and provided at its ends with connectors to ensure an electrical connection between the collector and the blade.
More precisely, the invention relates to a rotary-wing aircraft rotor, in particular a helicopter main rotor, of the type known in particular by EP-0 754 623 and FR 2 781 198 and comprising:
a hub, designed to be driven in rotation about an axis of the hub which is the axis of rotation of the rotor,
at least two blades, each of which is connected to the hub by a link member that is substantially radial with respect to the axis of rotation, and whose radially outer end is shaped like a fork in which the corresponding blade has its root held by two blade pins substantially parallel with each other and each one traversing aligned bores in the fork and the blade root, at least one blade being foldable on one side of the rotary wing aircraft and having at least one detachable blade pin, such that the withdrawal of the said detachable pin from the blade root and from the fork of the link member, after withdrawing at least a first detachable member for retaining the said detachable blade pin in the said fork, allows the pivoting of the blade about the other pin forming a blade pivot pin, and
an electrical connection installation comprising, for each blade, at least one electrical connecting cable connecting a first connector, carried by the hub and electrically connected, for example powered, on the latter, to a second connector on the blade and connected to at least one electrical equipment of the said blade, for example a de-icing or anti-icing equipment.
On a rotor according to EP 0 754 623, the connecting cable, for at least one manually foldable blade, comprises a first section, radially towards the outside, arranged like an overhead hook and extending from this blade to the corresponding link member, and connecting the second connector on this blade to a first end, in a radially outer position, of a second section of connecting cable, held substantially radially on this link member. This overhead hook of the connecting cable has a rounded cross section, possibly an armoured structure, and is connected to a plug of the second connector, this plug being connected to the socket of this second connector, this socket being fixed to the blade and connected to the icing or anti-icing equipment of that blade.
During the foldings of the blade, the pivotings of the blade in the radially outer fork of the corresponding link member can introduce damaging tensions in the overhead hook and in the second section of the connecting cable and in the second connector, and/or this overhead hook can oppose a complete folding of the blade.
In order to overcome this disadvantage, it is provided in EP 0 754 623 that the plug of the second connector, at the corresponding end of the overhead hook of the connecting cable, is connected in a detachable manner to the socket of the second connector, which is fixed on the blade. In fact, it is not recommended to give this overhead hook a length sufficient to allow the complete folding of the blade without disconnection at this connector, because an overhead hook of such length would have large forces applied to it and would be subjected to ample flutter movements, favouring its unwanted catching on adjacent components, such as blade root pendular anti-vibration devices, or drag dampers, on a rotor in rotation, on which the corresponding blade carries out angular deflections in pitch, flapping and drag.
Consequently, if it is desired to retain the advantages procured by the other characteristics of the connection installation described in EP 0 754 623, which can be referred to advantageously for more information, it is not possible to avoid manual disconnections and connections between the plug and the socket of the second connector in the case of manual folding or unfolding (or deployment) of the blades, before the folding and after the return of a blade to the flight configuration position respectively.
FR 2 781 198 proposes improvements to rotors with foldable blades and an electrical de-icing installation according to EP 0 754 623, in particular in order to reduce the stresses and/or movements of the connecting cable in its overhead hook section connecting the link member to the second connector on the blade, when the rotor is rotating and during the operations of folding and unfolding the blades.
For this purpose, according to FR 2 781 198, an elongated part of this overhead hook, of substantially flattened rectangular cross section, whose biggest dimension is oriented substantially parallel with the axis of rotation of the rotor, is held in a member, mounted in a fixed manner or pivoting about the folding spindle, in the substantially axial extension of this folding spindle, and arranged as a fork in which the said elongated part of flattened cross section is engaged and held by at least one elastic tab. This retaining fork prevents the displacements of the overhead hook on either side of the folding spindle, during a blade folding or unfolding, which prevents torsions harmful to this section of connecting cable, and it is no longer necessary to disconnect the link between the overhead hook and the de-icing equipment at the level of the second connector, before the folding of the blade, provided that the length of this overhead hook is sufficient without being so long that it generates the said disadvantages (flutter and unwanted catching).
But the flattened rectangular cross section of this overhead hook section of cable above the link between the blade root and the link member can generate a certain aerodynamic drag and cause a disturbing slipstream phenomenon. Furthermore, considering the angular movements, in particular of flapping of this section of cable and of its mechanical link with the link member, when that latter and the blade are carrying out these angular movements, it has proved necessary to form recesses in the periphery of a profiled dome covering the rotor head, and this amplifies the said slipstream phenomenon.
The basic problem for the invention is to overcome these disadvantages whilst avoiding the disconnection between the connecting cable and the second connector on the blade, for the folding of the latter, and avoiding the formation of a disturbing slipstream, caused by recesses in the profiled dome surmounting the rotor head and by a section of connecting cable with a flat profile oriented substantially parallel with the axis of the rotor.
For this purpose, the rotary wing aircraft rotor according to the invention, of the type described above, is characterized in that the connecting cable, for at least one foldable blade, comprises a first flexible section, of essentially cylindrical shape with rounded cross section, preferably substantially circular, connecting the said second connector to a first end, in a radially outer position, of a second section, held on the corresponding link member, of the said connecting cable, whose first section comprises a releasable part which, in the flight configuration of the blade, is maintained above the detachable blade pin by holding means tied to the said detachable blade pin, and also detachable to be able to be withdrawn before the folding of the blade, the said holding means being arranged in such a way as to allow a manual release of the releasable part before their withdrawal, such that the said releasable part is manually released from the said holdin
Certain Nicolas
Coisset Eric
Eurocopter
Henderson & Sturm LLP
Verdier Christopher
LandOfFree
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