The present invention relates to a segmented structure.
This segmented structure comprises at least two panels connected together and intended for deployment in space.
Although not exclusively, the present invention applies more particularly to a segmented structure forming part of a telecommunication satellite antenna reflector, in particular to a large antenna reflector, functioning in high frequency bands. The size of the reflector is inversely proportional to the frequency (at constant gain). Such an antenna reflector generally comprises a rigid structure (referred to as the shell) provided with a reflective surface and reinforcement means at the rear of this surface, which participate in the holding of the shell and in the connection to the satellite.
The large size of the shell of such a reflector poses problems of space requirement when a satellite provided with such a reflector is sent into space by means of a space launcher.
Thus, for rigid reflectors having diameters of several metres, a segmented structure is provided, provided with a plurality of panels, in particular a structure with three panels comprising a middle panel and two end panels.
This segmented structure also comprises a deployment device for each end panel, which is suitable for bringing the end panel, relative to the main panel:
In such a segmented structure, each end panel can therefore adopt a storage position for transport in the space launcher and a deployed position when the satellite is in space.
The present invention relates to a segmented structure, in particular for a satellite antenna reflector, comprising at least two panels and a deployment device making it possible to carry out in space effective and advantageous deployment of these two panels.
According to the invention, said segmented structure of the type comprising:
Thus, by virtue of the invention, the secondary panel of the segmented structure may be deployed effectively and advantageously in space, from the storage position to the deployed position, as specified below.
Moreover, in a preferred embodiment, the deployment device also comprises at least one dry-friction damper, fixed by means of auxiliary hinges, respectively, by a first of the ends thereof to the rear face of the secondary panel and by a second of the ends thereof to the rear face of the main panel.
Said first and second springs may have various features, in particular, advantageously:
Moreover, advantageously, at least one of said first and second hinges comprises at least one resilient element producing flexibility in a plane substantially parallel to the mid-plane of the main panel. In addition, advantageously, the axes of rotation of the first and second hinges of each of the linking arms of the parallelogram system are suited to geometric characteristics of the segmented structure so that the secondary panel follows the profile of the main panel during movement. Furthermore, preferably, said first hinges of the linking arms of the parallelogram system are arranged substantially at the centre of gravity of the secondary panel.
Moreover, in a first embodiment, said auxiliary guiding means comprise:
Furthermore, in a second embodiment, said auxiliary guiding means comprise at least two guide rails arranged on the rear face of the main panel so as to allow the secondary panel to slide on said guide rails, said guide rails being configured so as to guide the secondary panel to the deployed position, during the end guidance, and the parallelogram system (also forming part of the auxiliary guiding means) is configured so as to press said secondary panel on said guide rails and to move said panel in order to implement the end guidance.
Moreover, in a preferred embodiment, the segmented structure comprises:
The present invention also relates to:
The present invention also relates to a method for deploying a segmented structure as aforementioned.
According to the invention, this method comprises successive steps consisting, during deployment from the storage position to the deployed position, of:
In a first variant, step b) consists of moving said secondary panel towards said main panel by reeling at least one cable connected by one of the ends thereof to the secondary panel and by the other of the ends thereof to the main panel, at respective contact faces, by means of at least one reel device.
Furthermore, in a second variant, step b) consists of pressing and sliding the secondary panel on at least two guide rails arranged on the rear face of the main panel, as far as the deployed position, by means of said parallelogram system.
The figures of the accompanying drawings will give a clear understanding of how the invention can be implemented. In these figures, identical references designate similar elements.
The segmented structure 1, illustrating the invention and depicted schematically in
More precisely, the present invention relates to a segmented structure 1 of the type comprising:
This deployment device 5 is suitable for bringing the associated secondary panel, for example the secondary panel 3, into one or other of the following two positions, relative to the main panel 2:
In the description of the present invention:
In the preferred embodiment, depicted in the figures, the segmented structure 1 comprises:
In the situation in
According to the invention, each of the deployment devices 5 of the segmented structure 1 comprises:
Such a deployment device 5 makes it possible to perform an effective and advantageous deployment of the secondary panel 3, 4, with which it is associated, from the storage position P1 to the deployed position P2, as specified below.
The deployment is then effected by a parallelogram system 6 fixed on the one hand to a peripheral zone of the rear face 2B of the middle main panel 2 and on the other hand to the rear face 3B, 4B of the deployable secondary panel 3, 4. The deployment movement described by the secondary panel 3, 4 in the reference frame of the main panel 2 is a circular translation movement. The parallelogram 9 has, at each end, hinges 10 and 12 allowing the secondary panel 3, 4 to press against the main panel 2. The point of attachment G (
The deployment device 5 of a secondary panel 3, 4 further comprises at least one dry-friction damper 17 (a so-called Coulomb damper). This dry-friction damper 17 is fixed, by means of auxiliary hinges 18 and 19 respectively, as depicted schematically in
Such a damper 17 makes it possible to achieve control of the deployment speed and damping of the end-of-travel oscillations.
The linking arms 7 and 8 of the parallelogram 9 can be produced as a honeycomb sandwich or carbon-fibre tube. Since the mechanical forces on the linking arms 7 and 8 are low, the linear density of the arms 7 and 8 is also low. In a preferred embodiment, the interfaces 20 (
The motorisation of the first part of the kinematics, that is to say the deployment of the secondary panel 3, 4 with the parallelogram 9, is implemented by means of springs 11 and 13 that have suitable characteristics and are prestressed so as to have sufficient energy to effect the movement. These springs 11 and 13 are released when usual stacking points of the secondary panel 3, 4 are released.
The springs 11 are fixed, for example via a part 22 in the form of projecting stud, to a structure element 23, for example of planar form, which is rigidly connected to the rear face 3B of the secondary panel 3 and substantially orthogonal to said rear face, as depicted in
These springs 11 and 13 furthermore have the characteristics specified below.
Concerning the material used for the manufacture of the springs 11 and 13, a high modulus of resilience, satisfactory strength and good resistance to bending are sought. Thus it is possible to use a 45Si7 steel alloy (leaf spring) or the “piano wire” type spring for the springs 11 and 13. Furthermore, in order to have a Young's modulus independent of the temperature, it is possible to use Elinvar (steel with 33% nickel, 12% chromium, 1.2% manganese).
It is also possible to use for the springs 11 and 13 composite materials, based on glass fibres or carbon fibres, that have advantageous strength and mass characteristics.
Apart from the choice of the material, the performances of the springs 11 and 13 can also be improved by a surface treatment of the material. This is because the springs put the surface layers of the material under compression and traction, producing risks of fatigue failure. This treatment may for example be prestressing blasting on a metal material.
In addition, the springs 11 and 13 are preferably provided with a flexible thermal shield.
Furthermore, said hinges 10 and 12 comprise respectively resilient elements 25 (
Moreover, the axes of rotation of the hinges 10 and 12 are suited to the characteristics of the segmented structure 1 so that the secondary panel 3, 4 follows the profile of the main panel 2 during rotation.
More precisely, as depicted in
More precisely, in the example depicted in these figures, the longitudinal axis L:
The hinges 10 and 12 may be produced with springs of the leaf type (bending) or with cylindrical spirals (twisting) made of metal, composite or ceramic material. A deployment device 5 as described above, comprising in particular such hinges 10 and 12, has numerous advantages, and in particular:
Moreover, said auxiliary guiding means 15, 16 intended to implement the end guidance from the position PI may be produced in various ways.
In a first embodiment, the auxiliary guiding means 15 comprise, as depicted highly schematically in
Preferably, the auxiliary guiding means 15 comprise a plurality of associated cable 28 and reel device 29 assemblies.
This first embodiment makes it possible to effect the end guidance of the secondary panel 3, and then to fix the secondary panel 3 to the main panel 2 with the required precision and safety of operation. By means of a dynamic study, it is possible to evaluate the resonant frequencies of the cables 28 and to provide stacking points produced for example by aramid fibre cut by a hot wire. The separation between the main panel 2 and the secondary panel 3 is very small with this first embodiment, given the very small space requirement of the cables 28. The useable payload (during launch by space launcher) is therefore optimised to the maximum.
Furthermore, in a second embodiment, depicted schematically in
Thus, through a suitable prestressing of the springs 11 and 13, the approach end movement of the secondary panel 3, 4 on the main panel 2 is achieved. By resting on the two guide rails 30 and 31 between each secondary panel 3, 4 and the main panel 2 the expected kinematics can be produced. In addition, the friction generated by said resting could constitute a boost to the damping generated by the damper 17 or even replace it. A suitable usual fixing system (not shown) allows automatic fixing of the secondary panels 3, 4 to the main panel 2.
This second embodiment, which has motorisation incorporated in the kinematic joints, has the advantage of eliminating any motorisation and control. For the springs 11 and 13, materials are chosen having stiffness characteristics, as a function of temperature, compatible with requirements. Furthermore, flexible thermal shields can be provided to limit the temperature range experienced by the springs 11 and 13. This second embodiment is therefore simpler (no cable) and less expensive in terms of manufacture and integration. In addition, it is by design lighter (no motor, nor generation of electrical energy) and more compact.
According to the context of use, one or other of the first and second aforementioned embodiments may prove to be the more advantageous.
The devices 5 for deploying the segmented structure 1, associated with the various secondary panels 3 and 4 of this segmented structure 1, therefore make it possible to achieve deployment of the segmented structure 1 from a fully stowed position (in which the secondary panels 3 and 4 are in a storage position P1 as depicted in
The deployment device 5 also comprises means that are not shown (for example a central unit) for controlling in particular the electric motor of the reel device 29.
Moreover, the segmented structure 1 comprises usual means (not shown) for holding the various panels 2, 3 and 4 in the storage position P1. These holding means are released before deployment, so that each deployment device 5 can implement the deployment specified below.
The functioning of the deployment device 5, for deploying one 3 of said secondary panels 3, 4 from the storage position P1 of
More particularly,
It should be noted that, once the deployment movement has been effected (step a), the docking and the end guidance of the secondary panel 3 on the main panel 2 is effected by a rotation almost perpendicular to the first rotation. Motorisation of the docking can be effected in several ways.
In the aforementioned first embodiment comprising the auxiliary guiding means 15, step b) consists of moving the secondary panel 3 towards the main panel 2 by reeling at least one cable 28 connected by one of the ends thereof to the secondary panel 3 and by the other of the ends thereof to the main panel 2, at respective contact faces 3C and 2C, by means of a reel device 29 (
Furthermore, in the aforementioned second embodiment comprising the auxiliary guiding means 16, step b) consists of pressing and sliding the secondary panel 3 on the guide rails 30 and 31, by means of said parallelogram system 6, as far as the deployed position P2.
The same deployment method is used for the secondary panel 4 so as ultimately to obtain a fully deployed position of the segmented structure 1, depicted in
Of course, the device 5 may also bring the segmented structure from the deployed position P2 to the storage position P1 if this were to prove necessary, for example for a validation operation, by performing the aforementioned operations in the reverse order (b, a), with each operation performed in the opposite direction.
Moreover, the segmented structure 1 may comprise means that are not shown for allowing a precise final positioning between a secondary panel 3, 4 and the main panel 2, for example in the situation in
The deployment device 5 has the advantage of simplifying the kinematic connection parts to the maximum and incorporating the deployment motorisation in the connections, without any control system. The hinges 10 and 12 do not require any particular mechanical adjustment or lubrication and do not risk seizure due to differential thermal expansion. Furthermore, dry-friction dampers 17 make it possible to control the deployment speed (in particular at the end of travel) and to prevent end-of-travel oscillation. Moreover, the use of metal, composite or ceramic materials makes it possible to guarantee an absence of degassing, and resistance to conditions in space (radiation, atomic oxygen, etc.).
Number | Date | Country | Kind |
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13/02970 | Dec 2013 | FR | national |
Filing Document | Filing Date | Country | Kind |
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PCT/FR2014/000266 | 12/10/2014 | WO | 00 |