Deployment structure for space

Abstract

The present invention provides a deployment structure for space such as a deployable solar cell paddle (1), said structure comprising a plurality of frame units (10) in which a film (30) on which mounted objects such as solar cells (40) are mounted on a mounting surface (31) is attached to a frame (20). The frame units (10) of the deployment structure for space are in a stacked state when stowed. The deployment structure for space comprises a protective material (60) wedged in so as to be crushed between the films (30) of adjacent frame units (10) when stowed.

Description

Space deployable structure

[0001] The present disclosure relates to stowable and deployable structures for space applications.

[0002] In recent years, small constellation satellite projects have emerged that aim to mass-produce small satellites and reduce costs. For medium- to large-sized satellites, the trend is toward simultaneous launches of multiple satellites to reduce costs. In this context, deployable structures for space, such as solar array paddles, are required to meet three requirements: low cost, mass productivity, and high packability.

[0003] One type of solar cell paddle has been widely used in the past, in which solar cells are mounted on the surface of a structure made of an aluminum honeycomb core sandwiched between carbon fiber skins. This type of solar cell paddle has many steps in the manufacturing process, making it difficult to achieve the elements of "low cost" and "mass production." This type of solar cell paddle also has limitations in terms of how thin it can be made, and it is also difficult to achieve the element of "high storage capacity."

[0004] Patent Document 1 describes a deployable solar cell paddle that is suitable for achieving the three elements described above. The deployable solar cell paddle described in Patent Document 1 is a flat-pack solar cell paddle. A flat-pack solar cell paddle is made by linearly connecting multiple films or multiple thin plates on which solar cells are mounted and folding them like bellows when stored. Patent Document 1 describes a configuration in which a compact frame is made by mechanically fastening beams of the same cross section made of carbon fiber, and multiple frame units are connected together, each frame unit having solar cells mounted on a flexible film made of a polymer material.

[0005] International Publication No. 2023 / 175858

[0006] In the deployable solar array paddle described in Patent Document 1, solar cells, which are made of a brittle material, are mounted on a flexible film. Therefore, protecting the solar cells from vibrations during launch and other vibration environments is an important technology. The present disclosure aims to provide a deployable space structure that uses a film on which mounted components such as solar cells are mounted, capable of protecting the mounted components from vibrations.

[0007] The deployable space structure according to the present disclosure comprises a plurality of frame body units, each having a film with an object mounted on its mounting surface attached to a frame body, and the frame body units are stacked when stored, and comprises a protective material that is sandwiched between the films of adjacent frame body units so as to be crushed when stored.

[0008] In the present disclosure, when the film is stored, the protective material is sandwiched between the films of adjacent frame units so as to be crushed, thereby preventing damage to the mounted objects on the film due to the effects of vibration.

[0009] FIG. 1 is a diagram of the first embodiment, showing a perspective view of the deployable solar paddle 1 when deployed. FIG. 2 is a diagram of the first embodiment, showing the deployable solar paddle 1 in a folded state. FIG. 3 is a diagram of the first embodiment, showing a schematic view of the structure of the frame body 20. FIG. 4 is a diagram of the first embodiment, showing the film 30 attached to the frame body 20. FIG. 5 is a diagram of the first embodiment, showing the deployable solar paddle 1 when stored. FIG. 6 is a diagram of the first embodiment, showing the D-D cross section of FIG. 5. FIG. 7 is a diagram of the first embodiment, showing the C1-C1 cross section of FIG. 4 when a protective material 60 is added. FIG. 8 is a diagram of the first embodiment, showing the D-D cross section of FIG. 5 when a protective material 60 is added. FIG. 9 is a diagram of the first embodiment, showing the back surface 32 of the mounting surface 31 of one frame body unit 10. FIG. 10 is an explanatory diagram of the influence of vibration when a protective material 60 is not added.

[0010] Embodiment 1. In embodiment 1, a deployable solar paddle 1 with solar cells mounted as mounted components will be used as an example of a deployable space structure. ***Explanation of Basic Configuration*** The basic configuration of the deployable solar paddle 1 will be described with reference to Figures 1 and 2. Figure 1 shows a perspective view of the deployable solar paddle 1 when deployed. Figure 2 shows the deployable solar paddle 1 in a folded and stored state. The deployable solar paddle 1 in Figure 1 converts solar energy into electricity and supplies the converted electricity to a satellite or a space system.

[0011] The deployable solar paddle 1 includes multiple frame units 10. As shown in FIG. 1, each of the multiple frame units 10 is aligned in a straight line when deployed. X, Y, and Z coordinates are shown in FIG. 1. In drawings where coordinates are shown, the coordinates correspond to each other. The deployable solar paddle 1 in FIG. 1 includes two rows of multiple frame units 10: a first row 101 and a second row 102, each row facing in a straight line direction 103. In the X, Y, and Z coordinates, when the deployable solar paddle 1 is deployed, the plane formed by the multiple light-receiving surfaces (described later) is the XY plane, and the Y-axis direction is the straight line direction 103. The Z-axis is one of the directions normal to the XY plane. The first row 101 includes multiple frame units 10. The second row 102 also includes the same number of frame units 10 as the first row 101. The deployable solar paddle 1 consists of two rows, a first row 101 and a second row 102, but the deployable solar paddle 1 may be configured with one row or three or more rows. Furthermore, the number of frame units 10 that make up the first row 101 and the second row 102 is not limited.

[0012] Two frame body units 10 adjacent to each other in the linear direction 103 when deployed may be referred to as one frame body unit 10 and the other frame body unit 10. FIG. 1 shows an enlarged view of a region 501 of the deployable solar paddle 1 and an enlarged view of a region 502. The enlarged view of region 501 shows the hinge connection between one frame body unit 10 and the other frame body unit 10. The enlarged view of region 502 shows one frame body unit 10 in which a plurality of solar cells 40 are arranged. As shown in the enlarged view of region 501, in the first row 101, one frame body unit 10 is connected to the other adjacent frame body unit 10 by a hinge 50 when deployed. The same is true for the second row 102.

[0013] As shown in Figure 2, one frame body unit 10 rotates around the hinge 50 to overlap the other frame body unit 10 so as to cover it. Multiple frame body units 10 can be stored in layers by one frame body unit 10 covering the other frame body unit 10. In the deployable solar cell paddle 1, the positions of the hinges 50 are alternately located at the peaks of the mountains and the bottoms of the valleys of the multiple frame body units 10, so that the multiple frame body units 10 are ultimately stacked and folded. In other words, the multiple frame body units 10 are accordion-folded so that the frame body units 10 are stacked. Here, the direction of the peaks is in the Z-axis direction, and the direction of the valleys is opposite to the Z-axis direction.

[0014] The frame unit 10 will now be described. As shown in FIG. 1, each of the plurality of frame units 10 includes a frame 20 and a film 30.

[0015] <Frame 20> Figure 3 is a schematic diagram showing the structure of the frame 20. The frame 20 has a frame shape. From the viewpoint of mass production, the frame 20 is composed of beams with a simple cross-sectional shape. The beams can be made of metal or carbon fiber. The frame 20 is formed, for example, into a polygonal shape by combining multiple beams by mechanical fastening or adhesive bonding. The frame 20 shown in Figure 3 is formed into a square frame shape by multiple beams with L-shaped cross sections. Note that the L-shaped cross section is an example, and the cross-sectional shape is not limited. Figure 3 shows cross sections A-A and B-B. In the frame 20, the frame shape forms an opening 21.

[0016] <Film 30> Figure 4 shows the film 30 attached to the frame 20. The solar cell 40 is omitted from Figure 4. Figure 4 shows the C1-C1 cross section, the C2-C2 cross section, and the film 30 in an unfolded state. The C1-C1 cross section and the C2-C2 cross section correspond to the A-A cross section and the B-B cross section in Figure 3. The film 30 is made of a polymeric material and is flexible. In Figure 4, the film 30 is indicated by a dashed line. In the following drawings, the film 30 may also be indicated by a dashed line. The film 30 is attached flat to the bottom surface of the frame 20, which has an L-shaped cross section. The film 30 appears as a mounting surface 31 in the opening 21 formed by the frame shape of the frame 20. As in Figure 1, multiple solar cell cells 40 are mounted on the mounting surface 31 of the film 30.

[0017] <Solar Cell 40> A plurality of solar cells 40 are mounted on the mounting surface 31 of the film 30. As shown in Fig. 1 , a plurality of solar cells 40 arranged on the film 30 of one frame unit 10 constitute an electric circuit 43. Each of the plurality of trapezoidal shapes shown in the frame unit 10 in Fig. 1 is a solar cell 40. The electric circuit 43 outputs solar-generated power from an output line 44.

[0018] ***Explanation of the effects of the basic configuration*** <Issues with conventional rigid panel types> - Rigid panels require many manufacturing processes, resulting in long construction times and high costs. - Solar cell mounting must also be done on a panel-by-panel basis, making continuous manufacturing unsuitable for mass production. - There is a limit to how thin the panel can be made to ensure rigidity and strength. - To save space when mounting on a satellite or space system, the size of each panel must be reduced, so the thickness of the rigid panel is a bottleneck for rigid panel-type solar cell paddles. If you try to ensure sufficient light-receiving area due to the thickness of the rigid panel, the storage height in the stacking direction of the panels becomes too high when folded like a folding screen for storage.

[0019] <Effects of Basic Configuration> The above configuration provides superior low-cost, space-saving, and mass-producible properties compared to the rigid panel type widely used in the past. In the configuration of the deployable solar paddle 1, the frame body 20 can be constructed by mechanically fastening together metal or carbon fiber beams with the same simple cross-sectional shape that are suitable for mass production. This makes it easy to ensure the rigidity of the beams, and allows the thickness of the frame body unit 10, which corresponds to one panel, to be thin. In other words, the thickness of the frame body 20 can be thin. In the deployable solar paddle 1, multiple solar cells 40 are mounted on the film 30. This configuration allows for continuous manufacturing compared to the rigid panel type, where productivity is divided into panels. This ensures low cost and mass productivity.

[0020] ***Explanation of Light-Receiving Surface Spacing*** Figure 5 shows the deployable solar cell paddle 1 when stored. Figure 6 shows the D-D cross section of Figure 5. Referring to the bottom frame unit 10 in Figure 6, the mounting surface 31 of the film 30 is located below the frame body 20 in the downward direction 34, which is the direction from the mounting surface 31 toward the back surface 32 of the mounting surface 31. The back surface of the light-receiving surface 41 of each solar cell 40 of the multiple solar cell units 40 is attached to the mounting surface 31. As shown in Figure 6, taking the second frame unit 10 from the top and the other frame unit 10 third from the top as an example, when stored, the entire light-receiving surfaces 42 formed by the light-receiving surfaces 41 of the solar cell cells 40 face each other. When stored as shown in Figure 6, the entire light-receiving surfaces 42 face each other, which has the following effects.

[0021] In the case of the bottommost frame body unit 10 in Fig. 6, the direction from the mounting surface 31 toward the back surface 32 of the mounting surface 31 is the downward direction 34, but in the case of the frame body units 10 such as the second and fourth from the top in Fig. 6, the direction from the mounting surface 31 toward the back surface 32 of the mounting surface 31 is the opposite direction 35. In the following explanation of the effects, the bottommost frame body unit 10 in Fig. 6 will be used as an example, so in the case of the frame body units 10 such as the second and fourth from the top in Fig. 6, the downward direction 34 and the opposite direction 35 must be interpreted as being reversed.

[0022] ***Explanation of the Effect of Ensuring Light-Receiving Surface Spacing*** The light-receiving surfaces 41 of the solar cells 40 are covered with cover glass to prevent radiation degradation in the space environment. Therefore, the cover glass covering the light-receiving surfaces 41 is at high risk of mechanical damage due to contact with other components in the vibration environment during rocket launch. Note that when solar cells 40 with high radiation resistance are used, the light-receiving surfaces 41 may not be covered with cover glass. Because the solar cells 40 are also made of fragile materials, in this case, there is a risk of mechanical damage to the solar cells 40. However, because the mounting surface 31 of the film 30 is located below the frame 20 in the downward direction 34, which is the direction from the mounting surface 31 toward the back surface 32 of the mounting surface 31, a certain amount of spacing can be maintained between the opposing entire light-receiving surfaces 42. Therefore, even without any components or materials that directly protect the light-receiving surfaces, ensuring a spatial distance between the entire light-receiving surfaces 42 can prevent contact between the entire light-receiving surfaces 42 and damage to the entire light-receiving surfaces 42 to some extent. Therefore, there are advantages in terms of cost and mass production.

[0023] 6, when the deployable solar cell paddle 1 is stowed, the light-receiving surface spacing 45 between the entire light-receiving surfaces 42 is set to be at least twice the thickness of the frame body 20. Here, the thickness of the frame body 20, in terms of the bottom frame body unit 10 in FIG. 6, is the maximum width 36 in the downward direction 34 and in the direction 35 opposite the downward direction 34. As shown in FIG. 6, the back surfaces 32 of the light-receiving surfaces 41 of the solar cells 40 can be placed back-to-back via the respective films 30, and the spacing between the entire light-receiving surfaces 42 can be ensured to be at least twice the thickness of the frame body 20. As a result, when the deployable solar cell paddle 1 is stowed, the spacing between the entire light-receiving surfaces 42 of adjacent frame body units 10 can be maintained. Therefore, in this respect, it has the same effect as the above-mentioned configuration in which "the mounting surface 31 of the film 30 is located lower than the frame body 20 in the downward direction 34."

[0024] ***Description of Protective Material 60*** A protective material 60 is added to the basic configuration of the deployable solar paddle 1. FIG. 7 shows the C1-C1 cross section of FIG. 4 when the protective material 60 is added. FIG. 8 shows the D-D cross section of FIG. 5 when the protective material 60 is added. FIG. 9 shows the back surface 32 of the mounting surface 31 of one frame body unit 10. As shown in FIGS. 7 and 8, the protective material 60 is disposed on the back surface 32 of the mounting surface 31 of the film 30 in each frame body unit 10. Also, as shown in FIG. 9, in the first embodiment, a plurality of protective materials 60 are uniformly disposed in each frame body unit 10. Note that the arrangement of the protective materials 60 does not have to be uniform. For example, the arrangement intervals of the protective materials 60 may be changed depending on the position within the back surface 32. In this way, localization and uneven distribution of the protective materials 60 are permitted. Furthermore, the shape of the protective materials 60 may be changed depending on the position within the back surface 32. In the first embodiment, the protective material 60 is disposed in the same position in each frame unit 10. However, the position of the protective material 60 in each frame unit 10 does not necessarily have to be the same. For example, the protective material 60 in each frame unit 10 may be disposed in mirror symmetry or line symmetry. Furthermore, the thickness 61 of the protective material 60 is thicker toward the center of the frame 20 and thinner toward the end closer to the beam of the frame 20. However, even at the end, the thickness of the protective material 60 is thicker than half the distance 38 (see FIG. 8 ) between the two films 30 whose back surfaces 32 face each other. The protective material 60 is made of a material that satisfies the conditions of being lightweight, flexible, durable in a space environment, and having resilience. Specifically, the protective material 60 is made of a porous polymer material. For example, the protective material 60 is made of foamed polyimide.

[0025] As described above, when the frame body units 10 are aligned in a straight line during deployment, they are folded in an accordion-like manner during storage. This causes the mounting surfaces 31 of the films 30 of adjacent frame body units 10 to face each other, or the back surfaces 32 of the mounting surfaces 31 to face each other. Therefore, as shown in FIG. 8 , when the frames are folded in an accordion-like manner during storage, the protective materials 60 are sandwiched between the back surfaces 32 of the films 30 of adjacent frame body units 10. In this case, in the first embodiment, the positions of the protective materials 60 arranged on the frame body units 10 are the same, so the protective materials 60 provided on the two films 30 whose back surfaces 32 face each other overlap. Because the thickness of the protective material 60 is greater than half the distance 38 between the two films 30, the protective material 60 is sandwiched between the back surfaces 32 of the two films 30 in a crushed manner.

[0026] Since the protective material 60 is sandwiched between the back surfaces 32 of the two films 30 in a crushed manner, the film 30 is pressurized from the back surface 32 side by the restoring force of the protective material 60 and the tension of the other film 30 facing back to back, and the mounting surface 31 side becomes convex and tensioned.

[0027] ***Effects of the Protective Material 60*** <Issues When the Protective Material 60 Is Not Included> - When vibrations are applied to the deployable solar paddle 1 during storage, localized buckling deformation may occur in the film 30. The entire surface of the film 30 is not covered with solar cells 40; there are gaps where no solar cells 40 are present. Buckling deformation may occur in these gaps. If localized buckling deformation occurs in the film 30, the solar cells 40 near the buckling deformation may be damaged. - As shown in Figure 10, when vibrations are applied to the deployable solar paddle 1 during storage, the films 30 in each frame unit 10 vibrate, which may cause adjacent films 30 to interfere with each other. In particular, two films 30 whose back surfaces 32 face each other are close to each other at a distance 38, making them prone to interference. On the other hand, as described in the explanation of the effect of ensuring light-receiving surface spacing, two films 30 whose mounting surfaces 31 face each other are less likely to interfere with each other because they have a maximum width 36. However, there is a possibility that interference may occur due to vibration, and if interference occurs, there is a possibility that the solar cell 40 may be damaged.

[0028] <Effects of Providing the Protective Material 60> When the deployable solar paddle 1 is stowed, the protective material 60 is sandwiched between the back surfaces 32 of the two films 30 in a crushed manner. This maintains the convex shape of the film 30. As a result, local buckling deformation of the film 30 is prevented even when vibration is applied. When the deployable solar paddle 1 is stowed, the protective material 60 is sandwiched between the back surfaces 32 of the two films 30 in a crushed manner. This results in the two films 30 and the sandwiched protective material 60 becoming integrated. In other words, the tension of the film 30 and the restoring force of the protective material 60 form an integrated structure with the protective material 60 and the two films 30 in a tension structure, back-to-back. Therefore, when vibration is applied, a pressure is generated in this structure as an internal force, and the damping effect of the protective material 60 provides a damping effect against out-of-plane vibrations due to dynamic response, thereby suppressing the vibration response of the film 30. As a result, interference between adjacent films 30 can be prevented. In other words, although the clearance between adjacent films 30 is narrow in a static state, the damping effect reduces the out-of-plane displacement in dynamic response compared to the out-of-plane displacement in dynamic response without this structure, even when static (initial shape) displacement is taken into account, so interference can be prevented. In addition, the protective material 60 is sandwiched between the two films 30 whose back surfaces 32 face each other, preventing interference.

[0029] ***Other Configurations*** <Variation 1> In the first embodiment, the deployable solar cell paddle 1 on which solar cells are mounted as mounted components has been used as an example of a deployable space structure. However, the deployable space structure is not limited to the deployable solar cell paddle 1, and may be a deployable space structure on which semiconductor elements or the like are mounted on film 30 as mounted components. As a specific example, the deployable space structure may be a deployment paddle for an antenna on which an antenna element is mounted as a mounted component.

[0030] The embodiments and modifications of the present disclosure have been described above. Some of these embodiments and modifications may be combined and implemented. Furthermore, one or more of them may be implemented partially. Note that the present disclosure is not limited to the above embodiments and modifications, and various modifications are possible as needed.

[0031] DESCRIPTION OF SYMBOLS 1 Deployable solar cell paddle, 10 Frame unit, 20 Frame, 21 Opening, 22 Shaft, 23 Shaft portion, 24 Protrusion, 25 Mechanical contact, 26 Pin, 27 Screw, 28 Nut, 29 Axial direction, 30 Film, 31 Mounting surface, 32 Back surface, 33 Through hole, 34 Downward direction, 35 Opposite direction, 36 Maximum width, 38 Distance, 40 Solar cell, 41 Light receiving surface, 42 Entire light receiving surface, 43 Electrical circuit, 44 Output line, 45 Light receiving surface interval, 50 Hinge, 60 Protective material, 61 Thickness.

Claims

1. This space-use deployable structure comprises multiple frame units, each having a film on which a mounting surface is attached to a frame, and when stored, the frame units are stacked on top of each other. When stored, the protective material is compressed and sandwiched between the films in adjacent frame units. Equipped with, A space-use deployable structure in which one of the films in adjacent frame units is pressurized by the tension of the other film and the restoring force of the protective material to maintain a convex shape.

2. The space-use deployable structure according to Claim 1, wherein the frame body has a polygonal frame shape.

3. When stored, the films in adjacent frame units are in a state where their mounting surfaces face each other, or their back surfaces face each other. The protective material is placed on the back surface of the film in each frame unit and is sandwiched between the back surfaces of the film when stored. The space-use deployable structure according to claim 1.

4. The protective material is arranged such that, when stored, the protective material provided on the two films, whose back surfaces face each other, overlaps. The space-use deployable structure according to claim 3.

5. The protective material has a thickness in the stacking direction in which each frame unit is stacked, increasing towards the center of the frame. A space-use deployable structure according to claim 3 or 4.

6. When unfolded, the frame units are arranged in a straight line, and when stored, they are folded like an accordion, so that the films in adjacent frame units face each other either with their mounting surfaces facing each other or with their back surfaces facing each other. A space-use deployable structure according to claim 3 or 4.

7. Each of the frame units is provided such that, when stored, there is a gap of a standard distance or more between the films whose mounting surfaces face each other. The space-use deployable structure according to claim 1.