Deployable Devices

Abstract

To provide a deployable device.SOLUTION: The invention relates to a spreadable device (10) including: a supporting structure (11); a mandrel (12) able to move in rotation with respect to the supporting structure (11) around a first axis Z; a membrane (13) able to shift from a rolled-up state rolled up around the mandrel along the first axis Z to a spread state spread along a second axis X substantially perpendicular to the first axis Z. The device comprises two fittings (14) secured to the mandrel (12) at their center, each one of which is arranged on both sides of the membrane (13) and comprising first stubs (15) on their periphery (16) of the two fittings (14), and one casing (17) extending between the two fittings (14). The casing (17) comprises second stubs (18) having a shape complementing a shape of the first stubs (15). The casing (17) is able to shift from a rolled-up state at least partially enveloping the membrane (13) in the rolled-up state to a spread state at least partially superposed on the membrane (13) in the spread state.SELECTED DRAWING: Figure 1

Description

[Technical field]

[0001] The present invention relates to a deployable device for tape springs. The invention is particularly related to the field of space exploration equipment with structures that need to be deployed in orbit, more specifically space exploration equipment for satellites, such as solar power generation, heat screens, etc. However, the invention can also be applied in any other field involving the deployment of structures. [Background technology]

[0002] In space exploration, tape springs are often used to achieve deployment. The tape spring is wound around a mandrel in a stowed (or wound) position. The deployment of the tape spring occurs autonomously as the tape spring unwinds spontaneously when the mandrel is free to rotate. Tape springs are known in the space exploration field as flexible tapes with an arc-shaped cross section with a radius of curvature that is convex on a first surface and concave on a second surface, and these tapes can essentially move from a wound state to a deployed state by their own elastic energy. There are various types of tapes, each with their own characteristics. Monostable tapes have a natural deployed position and require a retention force to hold them in the stowed position. Monostable tape springs therefore have a natural tendency to unfold back to the unwound state. The deployment of monostable tapes is often chaotic and uncontrolled. Bistable tapes have two natural positions, a wound position and a deployed position. Their deployment is linear and controlled.

[0003] If it is desired to deploy the structure using tape springs, the tape springs must hold the mass in the wound state and maintain the stiffness of the assembly during deployment. The mandrel may be connected to the bearing structures at both ends. This allows optimizing the effective surface area, e.g. the membrane on which the solar cells are arranged, wound around the mandrel, and also minimizes the interfaces that engage the bearing structures. This type of configuration meets the requirements associated with deployable devices related to the issue of compactness and optimization of stiffness and payload in the stowed state. Summary of the Invention [Problem to be solved by the invention]

[0004] In configurations known in the prior art, the axle is connected to a bearing structure at both ends, and the axle must be able to withstand the full load of launch. The load capacity of the axle is also limited, since the diameter is limited by the constraints of available storage volume.

[0005] This is particularly problematic for large deployable structures that require large launch loads.

[0006] To address the above mentioned problems, existing solutions are based on adding load locations to the centre of the mandrel. For example, a load band is connected to the mandrel to contribute to the load resistance. Depending on the size of the deployable structure, there may be two or three load bands. This results in a reduction of the effective surface area. Furthermore, the addition of further load locations affects the performance of the structure in terms of payload and frequency of deployment. Finally, adding load locations may pose a risk that the structure will not deploy. [Means for solving the problem]

[0007] The present invention seeks to alleviate all or some of the above mentioned problems by proposing a tape spring deployable device that is robust, compact and rigid in the wound state, capable of withstanding high launch loads, while ensuring a maximum effective surface area and being capable of deploying structures of large size.

[0008] To this end, one subject of the invention is a deployable device comprising a support structure, a mandrel rotatably movable about a first axis Z relative to the support structure, and a membrane capable of moving from a rolled-up state, wound around the mandrel along the first axis Z, to a deployed state, deployed along a second axis X substantially perpendicular to the first axis Z. According to the invention, the deployable device comprises two couplings, one on each side of the membrane, including first stubs at their periphery and fixed in the middle to the mandrel, and a wrapping material extending between the two couplings, the wrapping material including a second stub whose shape is complementary to that of the first stub, the wrapping material being capable of moving from a rolled-up state in which it at least partially envelops the membrane in the rolled-up state to a deployed state in which it is at least partially superimposed on the membrane in the deployed state.

[0009] As an advantageous feature, the packaging material is manufactured from a skin made of a composite material.

[0010] Advantageously, the wrapping material includes at least one reinforcement substantially parallel to the first axis Z.

[0011] Advantageously, the packaging material includes at least one flexible printed circuit and / or electronic component.

[0012] The present invention also relates to a deployable assembly comprising a deployable device as described above and two tape springs arranged on either side of the membrane and connected to the membrane, each of the tape springs being capable of moving from a wound state wound around a first axis Z when the deployable device is in a wound state to a deployed state deployed along a second axis X when the deployable device is in a deployed state.

[0013] As an advantageous feature, the membrane extends between two tape springs.

[0014] As an advantageous feature, the deployable assembly further comprises at least one stiffener extending between the two tape springs and capable of connecting the membrane to the tape springs.

[0015] As an advantageous feature, the wrapper is connected to two tape springs.

[0016] As an advantageous feature, the unfoldable assembly includes a roller configured to compress the wrapping material in the rolled up state.

[0017] The invention also relates to a satellite including at least one such deployable assembly.

[0018] The invention will be better understood and further advantages will become apparent on examination of the detailed description of one embodiment given by way of example and illustrated in the accompanying drawings, in which: FIG. [Brief description of the drawings]

[0019] [Figure 1] 1 shows a schematic representation of a deployable device according to the present invention in a rolled up state; [Diagram 2] 1 illustrates a schematic cross-section of a deployable device according to the present invention; [Diagram 3] 1 shows a schematic representation of a portion of a deployable assembly according to the present invention in a deployed state; [Figure 4] 1 shows a schematic representation of a deployable assembly according to the present invention in a rolled up state; [Diagram 5] 1 shows a schematic representation of a deployable assembly according to the present invention in a deployed state; [Figure 6] 1 illustrates diagrammatically a satellite including a deployable assembly according to the invention; DETAILED DESCRIPTION OF THE PREFERRED EMBODIMENTS

[0020] For clarity, identical elements are numbered the same in each drawing.

[0021] The present invention applies to monostable or bistable tape springs. Using monostable tape springs requires more effort to induce. Bistable tape springs are preferred because they unfold uniformly. Also, the tape spring stays wound in the wound state and unfolded in the unfolded state.

[0022] Furthermore, although the invention has been described with the non-limiting example of deployment on a satellite, it is applicable to any other field requiring deployment of structures. EXAMPLES

[0023] In Fig. 1 a deployable device 10 according to the invention is shown diagrammatically in a wound state. The deployable device 10 comprises a support structure 11, e.g. a bearing structure, e.g. the hull of a satellite. The deployable device 10 also comprises a spindle 12 which is rotationally movable relative to the support structure 11 about a first axis Z. The spindle 12 may be connected to the support structure by a fixed structure or by two legs, e.g. a tripod and a blade, during the launch phase of the satellite and then separated from the support structure 11.

[0024] The deployable device includes a membrane 13 that is movable from a rolled-up state, wound around a mandrel along a first axis Z, to a deployed state, deployed along a second axis X generally perpendicular to the first axis Z. The membrane 13 may include solar cells distributed over its surface.

[0025] According to the invention, the deployable device 10 comprises two fittings 14, one on each side of the membrane 13, with first stubs 15 at the periphery 16 of the fittings 14, fixed approximately in the middle to the mandrel 12, and a wrapping 17 extending between the two fittings 14, the wrapping 17 including a second stub 18 of a shape complementary to the shape of the first stub 15, the wrapping 17 being transferable from a rolled-up state in which it at least partially wraps around the membrane 13 in the rolled-up state to a rolled-up state in which it is at least partially superimposed on the membrane 13 in the rolled-up state. The two fittings 14 are advantageously fixed to the loading platform legs in the launch state, which constitute the contact points of the deployable device 10, which is folded during the launch phase. The wrapping 17 forms with respect to the membrane 13 an external mandrel of high inertia that wraps around the membrane 13. The wrapping 17 is therefore able to withstand launch loads. As shown, the fittings 14 are advantageously circular in shape. Other shapes, such as ovals, are possible, but the circular shape remains the most advantageous in terms of the space that the packaging material 17 takes up when rolled up and in the rolled up state.

[0026] In the case of the circular joint 14, the first stub 15 is arranged on its periphery 16, i.e. on the periphery of the joint, and is directed towards the outside of the joint to face the second stub 18 of the packaging material 17. The first stub 15 and the second stub 18 have complementary shapes to engage with each other. The term stub should be understood in a broad sense, and the second stub 18 may be a hole into which the first stub 15 is inserted when the packaging material 17 is wound. As another example, the second stub 18 of the packaging material 17 may be a pin, advantageously a conical pin, and the first stub 15 of the joint 14 may be a groove. When the packaging material 17 is in the wound state, the pin of the packaging material 17 is inserted into the groove of the joint. The packaging material 17 is thus held in the wound position wound around the mandrel 12. As the packaging material unfolds, the pin of the packaging material slides along and away from the groove of the joint, and in the unfolded state of the packaging material, the pin is completely away from the groove. The assembly of the first stub 15 and the second stub 18 may also be adhesively connected by a protrusion on the one hand and a loop of filament on the other hand, in other words, in this latter alternative form of stub forming an adhesive connection, the first stub 15 and the second stub 18 are adhesive elements.

[0027] On the left side of Fig. 2, a cross-section of a deployable device 10 according to the invention is shown diagrammatically. The wrapper 17 completely envelops the outside of the membrane 13. The wrapper 17 may also partially envelop the membrane 13, i.e. envelop a part of the outer surface of the membrane 13 in the rolled up state. As an advantageous feature, the wrapper 17 envelops the entire outer surface of the membrane 13 (as shown in the figure). The wrapper 17 may also envelop the membrane 13 in several overlapping turns. The latter configuration improves the resistance to launch loads.

[0028] As can be seen in Fig. 5, the wrapping material 17 in the unfolded state covers a part of the membrane 13. This part covered by the wrapping material 17 is not yet available as an effective surface area for adjusting the position of the solar cell. Therefore, a compromise is made between the length of the wrapping material 17 (i.e. the number of turns) and the effective surface area that cannot be used as is.

[0029] The packaging material 17 consists of a skin made of a composite material. Among the composite materials from which the packaging material can be formed, mention may be made of glass fiber, carbon fiber (valued for its robustness and light weight) or polymers of the polyaryletherketone (PAEK) polymer family, preferably of the polyetheretherketone (PEEK) type. Polyaryletherketones are a family of industrial thermoplastic polymers with good thermomechanical properties. Polyetheretherketones have a very high thermal stability. Also included are polyimides, imide-based polymers, which show thermal stability in a wide temperature range (e.g. -200 to +200 °C), suitable for use in the field of space exploration. For example, it may be Kapton (polyimide film), reinforced or not.

[0030] The wrapping material 17 is advantageously manufactured in the form of a lattice or net, or may be of knitted construction.

[0031] The assembly formed by the wrapping 17 and the joints 14 to which the wrapping 17 is fixed in the rolled up state is able to withstand tensor compressive loads during launch.

[0032] As shown diagrammatically in the right hand portion of FIG. 2, the membrane 13 can also support multiple lamellae of various shapes, such as an arc of a cylinder 31, an H-section 32, a honeycomb 33, a tube 34, etc.

[0033] FIG. 3 shows a schematic of a portion of a deployable assembly 20 according to the present invention in a deployed state.

[0034] As can be seen in this figure, the wrapper 17 may include at least one reinforcement 19 generally parallel to the first axis Z that may reinforce the mesh structure or lattice that forms the wrapper 17 .

[0035] The deployable assembly 20 includes one deployable device 10 and two tape springs 21, one disposed on each side of the membrane 13 and connected to the membrane, each tape spring 21 being movable from a wound state wound around a first axis Z when the deployable device 10 is in a wound state to a deployed state deployed along a second axis X when the deployable device 10 is in a deployed state.

[0036] In one advantageous embodiment, the wrapping material 17 is connected to two tape springs 21. The deployment of the tape springs 21 allows the wrapping material 17 to be deployed simultaneously.

[0037] In Fig. 4, the deployable assembly 20 according to the invention is shown diagrammatically in a rolled-up state. In the area of ​​the fitting 14, a first stub 15 is seen, the shape of which is complementary to a second stub 18 of the wrapper 17, which in the rolled-up state of the deployable device 10 engage with each other to keep the wrapper 17 in a rolled-up position around the fitting 14 and thus around the membrane 13, in order to wrap the membrane 13. The first stub 15 of the fitting is a protrusion and the second stub 18 of the wrapper 17 is an orifice arranged to receive the protrusion and to hold it in place in the orifice. The reverse is also conceivable. The first stub 15 may be an orifice and the second stub 18 a protrusion. In this case, the wrapper 17 must be designed such that the size of the protrusion (second stub 18) overlaps the orifice (first stub 15) of the fitting 14 when it is rolled up again and again around itself in the rolled-up state. The wrapper 17 thus forms the outer stem of the membrane 13 .

[0038] The unfoldable device 10 may further include a guide system for guiding the packaging material 17. The guide system consists of a spring 23 and a zone contact 24. The zone contact 24 rests on the spring 23, which in turn is connected to the support structure 11. The zone contact 24 at least partially envelops the packaging material 17 in the rolled up state. As an advantageous feature, the unfoldable device 10 includes two guide systems, one on each end of the packaging material 17. The guide systems ensure that the packaging material 17 fits properly in the rolled up position.

[0039] The deployable device 10 may also include a roller 25 configured to press the wrapping material 17 in the rolled up state. As an advantageous feature, the roller 25 is central. Such a roller 25 may be obtained using means known to the person skilled in the art, for example a finger pressing the wrapping material 17, said finger being connected to an arm connected to the support structure 11. For a solar generator with a width of 5-6 meters, the length of the wrapping material 17 may be, for example, 10 meters. The roller 25 pressing the wrapping material 17 restricts the movement and bending of the assembly. The roller 25 forms a point contact.

[0040] 5 shows a schematic representation of a deployable assembly 20 according to the invention in a deployed state. The deployable assembly 20 may further comprise at least one stiffener 22 extending between the two tape springs 21 and capable of connecting the membrane 13 to the tape springs 21.

[0041] The tape spring 21 serves as a support for the membrane 13, enabling it to move from a wound state to an unwrapped state.

[0042] The membrane 13 may be disposed between two tape springs 21 as seen in FIG. 5 and may be connected to the tape springs 21 via a reinforcement 22, but may extend beyond the tape springs 21 with or without the reinforcement 22.

[0043] The envelope 17 may also include at least one flexible printed circuit and / or electronic component, the presence of which provides an electrical connection between the membrane 13 and the satellite intended to supply electrical energy from the solar cells.

[0044] The present invention provides many advantages. The deployable assembly, through its design, is reversible and reusable any number of times. The package 17 is robust when the assembly is in the rolled up state, while at the same time remaining optimally compact and bulky. The package 17 is able to withstand launch loads without adding additional storage space, thus maintaining nearly all of its area as usable surface area.

[0045] FIG 6 shows a schematic representation of a satellite 60 including a deployable assembly 20 according to the present invention. Only a single deployable assembly 20 is shown in FIG 6. The satellite 60 may include multiple of these on different surfaces of the satellite or on the same surface depending on the available space. FIG 6 shows the deployable assembly 20 in a wound state with the membrane 13 and wrapper 17 wound around the mandrel 12. [Explanation of symbols]

[0046] 10 Deployable Devices 11 Support structure 12 Mandrel 13 membrane 14 Joints 15 First Stub 16 Periphery 17 Packaging material 18 Second Stub 19, 22 Reinforcement 20 Assembly 21 Tape spring 23 Spring 24 area contacts 25 Roller 31 Arc of cylinder 32 H-shaped cross section 33 Honeycomb 34 Tube 60 satellites

Claims

1. a support structure (11), - a mandrel (12) rotatably movable relative to said support structure (11) about a first axis Z; a membrane (13) capable of moving from a wound state, wound around said mandrel along said first axis Z, to a deployed state, deployed along a second axis X substantially perpendicular to said first axis Z, - two circular joints (14) arranged one on each side of said membrane (13) and including first stubs (15) on their periphery (16) and fixed centrally to said stem (12); a wrapper (17) extending between the two joints (14), the wrapper (17) comprising a second stub (18) whose shape is complementary to the shape of the first stub (15), the wrapper (17) being capable of moving from a rolled-up state in which the wrapper (17) at least partially envelops the membrane (13) in a rolled-up state in which the wrapper (17) is rolled around the periphery of the joints (14), to a rolled-up state in which the wrapper (17) is at least partially superimposed on the membrane (13) in a rolled-up state.

2. 2. The deployable device (10) according to claim 1, characterized in that the packaging (17) is made of a composite material skin.

3. 3. The deployable device (10) according to claim 1 or 2, characterized in that the packaging material (17) comprises at least one stiffener (19) substantially parallel to the first axis Z.

4. The deployable device (10) according to any one of claims 1 to 3, characterized in that said packaging material (17) contains at least one flexible printed circuit and / or electronic component.

5. - a deployable device (10) according to any one of claims 1 to 4, a deployable assembly (20) comprising two tape springs (21), one on either side of the membrane (13) and connected to said membrane, each of which is capable of moving from a wound state wound around a first axis Z when said deployable device (10) is in a wound state to a deployed state deployed along a second axis X when said deployable device (10) is in a deployed state.

6. 6. A deployable assembly (20) according to claim 5, characterized in that said membrane (13) extends between said two tape springs (21).

7. 7. The deployable assembly (20) according to claim 5 or 6, further comprising at least one stiffener (22) extending between the two tape springs (21) and capable of connecting the membrane (13) to the tape springs (21).

8. A deployable assembly (20) according to any one of claims 5 to 7, characterised in that a wrapping material (17) is connected to said two tape springs (21).

9. A deployable assembly (20) according to any one of claims 5 to 8, characterised in that it comprises a roller (25) arranged to press the wrapping material (17) in a rolled up state.

10. A satellite (60) comprising at least one deployable assembly (20) according to any one of claims 5 to 9.

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