A single-degree-of-freedom foldable tubular structure based on four spherical four-bar linkages

Abstract

The present invention discloses a single-degree-of-freedom foldable tubular structure based on four spherical four-bar linkages, comprising eight faces, namely the first face, the second face, the third face, the fourth face, the fifth face, the sixth face, the seventh face, and the eighth face; the first face, the second face, the third face, and the fourth face are connected end to end in sequence to form a first prism, and the fifth face, the sixth face, the seventh face, and the eighth face are connected end to end in sequence to form a second prism, and the second prism is arranged below the first prism; the four sides of the top of the second prism are connected to the four sides of the bottom of the first prism to form a spatial quadrilateral; the present invention can realize the conversion between spatial structures and spatial structures, plane structures and plane structures, or spatial structures and plane structures, and can realize complete folding or unfolding in some cases. The present invention has a degree of freedom of 1, and can complete folding and unfolding actions through a single drive, has a simple structure, is convenient to install and use, and has reliable movement.

Description

Technical Field

[0001] The invention relates to the field of foldable tubular structures, in particular to a single-degree-of-freedom, multi-layer foldable tubular structure based on origami structure. Background Art

[0002] Tubular structures have been widely used in aerospace, building structures, artworks and daily life due to their hollow and lightweight characteristics. However, due to their large space occupation and unstable transportation, they can often only be used in fixed occasions, which restricts their use in many fields.

[0003] The space foldable structure is a new type of structure born with the development of aerospace technology. It is in a folded and stored state during the launch process, with a small volume capacity. After entering orbit, the foldable structure can be unfolded into a larger operational working state according to the design. When returning or recovering, the structure can be folded and retracted again into the spacecraft. The space foldable structure using over-constrained mechanisms as basic units has the advantages of high rigidity, simple manufacturing, low cost, and high reliability.

[0004] Existing spatial foldable structures mainly involve folding on planes or curved surfaces, such as solar panels and satellite antennas, while the folding mechanisms involving volume are mainly obtained by non-rigid deformation. The deformation process is not conducive to control and is not easy to repeat. Existing body-shaped foldable structures using rigid deformation are either complex in structure, such as the foldable polyhedron structure driven by a regular polygon mechanism proposed by CM Gosselin and D. Gagnon-Lachance in 2006; or cannot be completely folded, such as Kiper and The foldable polyhedron was proposed in 2009. Therefore, the application of body-shaped deployable structures is relatively small at present, and there are some shortcomings such as inability to fold completely and small folding and unfolding ratio. Summary of the invention

[0005] The purpose of the present invention is to overcome the deficiencies in the prior art and provide a single-degree-of-freedom, multi-layer expandable tubular structure. The expandable tubular structure is small in size when folded and convenient for transportation, and has a large working space when opened to a working state as required; the entire structure has only one degree of freedom and simple motion control; it has the advantages of simple production and processing, convenient motion control, high reliability, etc., and is particularly suitable for packaging, storage, civil structures, aerospace and many other fields, and has important significance and broad application prospects.

[0006] The objective of the present invention is achieved through the following technical solutions:

[0007] A single-degree-of-freedom foldable tubular structure based on four spherical four-bar linkages comprises eight faces, namely, a first face, a second face, a third face, a fourth face, a fifth face, a sixth face, a seventh face and an eighth face; the first face, the second face, the third face and the fourth face are connected end to end in sequence to form a first prism, the fifth face, the sixth face, the seventh face and the eighth face are connected end to end in sequence to form a second prism, and the second prism is arranged below the first prism; the four sides at the top of the second prism are connected to the four sides at the bottom of the first prism to form a spatial quadrilateral;

[0008] The second side of the first surface is adjacent to the fourth side of the second surface and connected to each other through the first rotation pair; the second side of the second surface is adjacent to the fourth side of the third surface and connected to each other through the second rotation pair; the second side of the third surface is adjacent to the fourth side of the fourth surface and connected to each other through the third rotation pair; the fourth side of the first surface is adjacent to the second side of the fourth surface and connected to each other through the fourth rotation pair; the second side of the fifth surface is adjacent to the fourth side of the sixth surface and connected to each other through the fifth rotation pair; the second side of the sixth surface is adjacent to the fourth side of the seventh surface and connected to each other through the sixth rotation pair; the second side of the seventh surface is adjacent to the fourth side of the eighth surface and connected to each other through the seventh rotation pair; the fourth side of the fifth surface is adjacent to the second side of the eighth surface and connected to each other through the eighth rotation pair; the third side of the first surface is adjacent to the first side of the fifth surface and connected to each other through the ninth rotation pair; the third side of the second surface is adjacent to the first side of the sixth surface and connected to each other through the tenth rotation pair; the third side of the third surface is adjacent to the first side of the seventh surface and connected to each other through the eleventh rotation pair; the third side of the fourth surface is adjacent to the first side of the eighth surface and connected to each other through the twelfth rotation pair;

[0009] The first rotation secondary axis, the second rotation secondary axis, the third rotation secondary axis, and the fourth rotation secondary axis are parallel to each other; the fifth rotation secondary axis, the sixth rotation secondary axis, the seventh rotation secondary axis, and the eighth rotation secondary axis are parallel to each other;

[0010] The first surface, the second surface, the sixth surface, and the fifth surface are connected in sequence by the first rotational pair, the tenth rotational pair, the fifth rotational pair, and the ninth rotational pair to form a first spherical four-bar linkage; the second surface, the third surface, the seventh surface, and the sixth surface are connected in sequence by the second rotational pair, the eleventh rotational pair, the sixth rotational pair, and the tenth rotational pair to form a second spherical four-bar linkage; the third surface, the fourth surface, the eighth surface, and the seventh surface are connected in sequence by the third rotational pair, the twelfth rotational pair, the seventh rotational pair, and the eleventh rotational pair to form a third spherical four-bar linkage; the fourth surface, the first surface, the fifth surface, and the eighth surface are connected in sequence by the fourth rotational pair, the ninth rotational pair, the eighth rotational pair, and the twelfth rotational pair to form a fourth spherical four-bar linkage;

[0011] The first spherical four-bar linkage and the second spherical four-bar linkage share the tenth rotational pair, the second spherical four-bar linkage and the third spherical four-bar linkage share the eleventh rotational pair, the third spherical four-bar linkage and the fourth spherical four-bar linkage share the twelfth rotational pair, and the first spherical four-bar linkage and the fourth spherical four-bar linkage share the ninth rotational pair;

[0012] Define the upper left corner, upper right corner, lower right corner and lower left corner in the plane unfolded view of each face to be the first angle, the second angle, the third angle and the fourth angle respectively; wherein the sum of the angles of the third angle of the first face and the first angle of the sixth face is 180°, the sum of the angles of the fourth angle of the second face and the second angle of the fifth face is 180°, the sum of the angles of the third angle of the third face and the first angle of the eighth face is 180°, and the sum of the angles of the fourth angle of the fourth face and the second angle of the seventh face is 180°;

[0013] The folding and unfolding of the single-degree-of-freedom foldable tubular structure are performed around the ninth rotation pair, the tenth rotation pair, the eleventh rotation pair and the twelfth rotation pair. When folding, the first surface and the fifth surface rotate around the ninth rotation pair and the angle between the two surfaces gradually decreases, the second surface and the sixth surface rotate around the tenth rotation pair and the angle between the two surfaces gradually decreases, the third surface and the seventh surface rotate around the eleventh rotation pair and the angle between the two surfaces gradually decreases, and the fourth surface and the eighth surface rotate around the twelfth rotation pair and the angle between the two surfaces gradually decreases.

[0014] Furthermore, each component surface of the foldable tubular structure is a parallelogram, a trapezoid or a combination of the two.

[0015] Furthermore, by changing the parameters of the foldable tubular structure, different unfolding forms and folding forms can be achieved, and the parameters include the angles of each component surface and the side lengths of the spatial quadrilateral.

[0016] Furthermore, the mutual conversion between the spatial body structure and the spatial body structure, the mutual conversion between the plane structure and the plane structure, or between the spatial body structure and the plane structure is realized by changing the angle between the adjacent surfaces in the foldable tubular structure.

[0017] Furthermore, the foldable tubular structure can be arranged and extended in the axial direction.

[0018] Compared with the prior art, the technical solution of the present invention has the following beneficial effects:

[0019] 1. The present invention can realize the conversion between spatial structure and spatial structure, plane structure and plane structure, or spatial structure and plane structure, and can realize complete folding or unfolding in some cases.

[0020] 2. The present invention has a degree of freedom of 1, and can complete folding and unfolding actions through a single drive. It has a simple structure, is easy to install and use, and has reliable movement.

[0021] 3. The present invention is designed for functionality. The size of the unit structure can be designed according to actual needs. The size of the revolving pair can be adjusted at any time according to requirements, and the installation drive position can be arbitrarily selected according to actual requirements.

[0022] 4. The invention has a stable structure after unfolding and a certain load-bearing capacity; it has a small volume and a stable structure after folding, which is convenient for transportation and storage. During the folding or unfolding process, the tubular structure has a large internal space. BRIEF DESCRIPTION OF THE DRAWINGS

[0023] Figure 1-1 This is a component composition and planar development diagram of a foldable tubular structure composed of four spherical connecting rod mechanisms according to the first embodiment of the present invention.

[0024] Figure 1-2 , Figure 1-3 The schematic diagrams are respectively the fully expanded state and the fully folded state of the tubular structure of the first specific embodiment of the present invention. The structure is a polygonal planar structure in both the fully expanded state and the fully folded state.

[0025] Figure 1-4 to Figure 1-7 A schematic diagram showing the folding sequence of the tubular structure of the first embodiment from a fully expanded state to a fully folded state, Figure 1-4 Indicates the fully expanded state. Figure 1-5 and Figure 1-6 Indicates the intermediate state of folding, Figure 1-7 Indicates fully folded state.

[0026] Figure 1-8 The foldable tubular structure of the first embodiment of the present invention is used as a basic unit and is arranged and extended in the axial direction according to the above-mentioned arrangement and connection method to obtain a tubular structure.

[0027] Figure 2-1 This is a component composition and planar development diagram of a foldable tubular structure composed of four spherical connecting rod mechanisms according to the second embodiment of the present invention.

[0028] Figure 2-2 , Figure 2-3 The schematic diagrams are respectively the fully expanded state and the fully folded state of the tubular structure of the second specific embodiment of the present invention. The structure is a polygonal planar structure in both the fully expanded state and the fully folded state.

[0029] Figure 2-4 to Figure 2-7 A schematic diagram showing the folding sequence of the tubular structure of the second embodiment from a fully unfolded state to a fully folded state, Figure 2-4 Indicates the fully expanded state. Figure 2-5 and Figure 2-6 Indicates the intermediate state of folding, Figure 2-7Indicates fully folded state.

[0030] Figure 2-8 The tubular structure is obtained by taking the second embodiment of the present invention as a basic unit and arranging and extending it in the axial direction according to the above-mentioned arrangement and connection method.

[0031] Figure 3-1 This is a component composition and planar development diagram of a foldable tubular structure composed of four spherical connecting rod mechanisms according to the third embodiment of the present invention.

[0032] Figure 3-2 , Figure 3-3 The schematic diagrams are respectively the fully unfolded state and the fully folded state of the tubular structure of the third specific embodiment of the present invention. The structure is a tubular structure with a triangular cross section in the fully unfolded state and a polygonal planar structure in the fully folded state.

[0033] Figure 3-4 to Figure 3-7 A schematic diagram showing the folding sequence of the tubular structure of the third specific embodiment from a fully expanded state to a fully folded state, Figure 3-4 Indicates the fully expanded state. Figure 3-5 and Figure 3-6 Indicates the intermediate state of folding, Figure 3-7 Indicates fully folded state.

[0034] Figure 3-8 The tubular structure is obtained by taking the third embodiment of the present invention as a basic unit and arranging and extending it in the axial direction according to the above-mentioned arrangement and connection method.

[0035] Figure 4-1 This is a component composition and planar development diagram of a foldable tubular structure composed of four spherical connecting rod mechanisms according to a fourth embodiment of the present invention.

[0036] Figure 4-2 , Figure 4-3 The schematic diagrams are respectively the fully expanded state and the fully folded state of the tubular structure of the fourth specific embodiment of the present invention. The structure is a polygonal planar structure in both the fully expanded state and the fully folded state.

[0037] Figure 4-4 to Figure 4-7 A schematic diagram showing the folding sequence of the tubular structure of the fourth embodiment from a fully expanded state to a fully folded state, Figure 4-4 Indicates the fully expanded state. Figure 4-5 and Figure 4-6 Indicates the intermediate state of folding, Figure 4-7 Indicates fully folded state.

[0038] Figure 4-8 The tubular structure is obtained by taking the fourth embodiment of the present invention as a basic unit and arranging and extending it in the axial direction according to the above-mentioned arrangement and connection method.

[0039] Reference numerals:

[0040] For Example 1:

[0041] A1-first side, A2-second side, A3-third side, A4-fourth side, A5-fifth side, A6-sixth side, A7-seventh side, A8-eighth side;

[0042] M1-first rotation pair, M2-second rotation pair, M3-third rotation pair, M4-fourth rotation pair, M5-fifth rotation pair, M6-sixth rotation pair, M7-seventh rotation pair, M8-eighth rotation pair, M9-ninth rotation pair, M10-tenth rotation pair, M11-eleventh rotation pair, M12-twelfth rotation pair;

[0043] A1K3 - the third corner of the first face; A2K4 - the fourth corner of the second face; A3K3 - the third corner of the third face; A4K4 - the fourth corner of the fourth face; A5K2 - the second corner of the fifth face; A6K1 - the first corner of the sixth face; A7K2 - the second corner of the seventh face; A8K1 - the first corner of the eighth face;

[0044] A1L2-first surface, second side; A1L3-first surface, third side; A1L4-first surface, fourth side;

[0045] A2L2-second side, second edge; A2L3-second side, third edge; A2L4-second side, fourth edge;

[0046] A3L2-third side, second edge; A3L3-third side, third edge; A3L4-third side, fourth edge;

[0047] A4L2-the second side of the fourth surface; A4L3-the third side of the fourth surface; A4L4-the fourth side of the fourth surface;

[0048] A5L1-5th surface, first side; A5L2-5th surface, second side; A5L4-5th surface, fourth side;

[0049] A6L1-first side of the sixth surface; A6L2-second side of the sixth surface; A6L4-fourth side of the sixth surface;

[0050] A7L1-first side of the seventh surface; A7L2-second side of the seventh surface; A7L4-fourth side of the seventh surface;

[0051] A8L1-first side of the eighth surface; A8L2-second side of the eighth surface; A8L4-fourth side of the eighth surface;

[0052] For Example 2:

[0053] B1-first side, B2-second side, B3-third side, B4-fourth side, B5-fifth side, B6-sixth side, B7-seventh side, B8-eighth side;

[0054] N1-first rotation pair, N2-second rotation pair, N3-third rotation pair, N4-fourth rotation pair, N5-fifth rotation pair, N6-sixth rotation pair, N7-seventh rotation pair, N8-eighth rotation pair, N9-ninth rotation pair, N10-tenth rotation pair, N11-eleventh rotation pair, N12-twelfth rotation pair;

[0055] B1K3 - the third corner of the first face; B2K4 - the fourth corner of the second face; B3K3 - the third corner of the third face; B4K4 - the fourth corner of the fourth face; B5K2 - the second corner of the fifth face; B6K1 - the first corner of the sixth face; B7K2 - the second corner of the seventh face; B8K1 - the first corner of the eighth face;

[0056] B1L2-first surface, second side; B1L3-first surface, third side; B1L4-first surface, fourth side;

[0057] B2L2-second side, second edge; B2L3-second side, third edge; B2L4-second side, fourth edge;

[0058] B3L2-third side, second edge; B3L3-third side, third edge; B3L4-third side, fourth edge;

[0059] B4L2-the second side of the fourth surface; B4L3-the third side of the fourth surface; B4L4-the fourth side of the fourth surface;

[0060] B5L1-first side of the fifth surface; B5L2-second side of the fifth surface; B5L4-fourth side of the fifth surface;

[0061] B6L1-first side of the sixth surface; B6L2-second side of the sixth surface; B6L4-fourth side of the sixth surface;

[0062] B7L1-the first side of the seventh surface; B7L2-the second side of the seventh surface; B7L4-the fourth side of the seventh surface;

[0063] B8L1-first side of the eighth surface; B8L2-second side of the eighth surface; B8L4-fourth side of the eighth surface;

[0064] For Example 3:

[0065] C1-first surface, C2-second surface, C3-third surface, C4-fourth surface, C5-fifth surface, C6-sixth surface, C7-seventh surface, C8-eighth surface;

[0066] P1-first rotation pair, P2-second rotation pair, P3-third rotation pair, P4-fourth rotation pair, P5-fifth rotation pair, P6-sixth rotation pair, P7-seventh rotation pair, P8-eighth rotation pair, P9-ninth rotation pair, P10-tenth rotation pair, P11-eleventh rotation pair, P12-twelfth rotation pair;

[0067] C1K3 - the third corner of the first face; C2K4 - the fourth corner of the second face; C3K3 - the third corner of the third face; C4K4 - the fourth corner of the fourth face; C5K2 - the second corner of the fifth face; C6K1 - the first corner of the sixth face; C7K2 - the second corner of the seventh face; C8K1 - the first corner of the eighth face;

[0068] C1L2-first surface, second side; C1L3-first surface, third side; C1L4-first surface, fourth side;

[0069] C2L2-second side, second edge; C2L3-second side, third edge; C2L4-second side, fourth edge;

[0070] C3L2-third side, second edge; C3L3-third side, third edge; C3L4-third side, fourth edge;

[0071] C4L2-the second side of the fourth surface; C4L3-the third side of the fourth surface; C4L4-the fourth side of the fourth surface;

[0072] C5L1-first side of the fifth surface; C5L2-second side of the fifth surface; C5L4-fourth side of the fifth surface;

[0073] C6L1-first side of the sixth surface; C6L2-second side of the sixth surface; C6L4-fourth side of the sixth surface;

[0074] C7L1-the first side of the seventh surface; C7L2-the second side of the seventh surface; C7L4-the fourth side of the seventh surface;

[0075] C8L1-first side of the eighth surface; C8L2-second side of the eighth surface; C8L4-fourth side of the eighth surface;

[0076] For Example 4:

[0077] D1-first surface, D2-second surface, D3-third surface, D4-fourth surface, D5-fifth surface, D6-sixth surface, D7-seventh surface, D8-eighth surface;

[0078] Q1-first rotation pair, Q2-second rotation pair, Q3-third rotation pair, Q4-fourth rotation pair, Q5-fifth rotation pair, Q6-sixth rotation pair, Q7-seventh rotation pair, Q8-eighth rotation pair, Q9-ninth rotation pair, Q10-tenth rotation pair, Q11-eleventh rotation pair, Q12-twelfth rotation pair;

[0079] D1K3 - the third corner of the first face; D2K4 - the fourth corner of the second face; D3K3 - the third corner of the third face; D4K4 - the fourth corner of the fourth face; D5K2 - the second corner of the fifth face; D6K1 - the first corner of the sixth face; D7K2 - the second corner of the seventh face; D8K1 - the first corner of the eighth face;

[0080] D1L2-first surface, second side; D1L3-first surface, third side; D1L4-first surface, fourth side;

[0081] D2L2-second side, second edge; D2L3-second side, third edge; D2L4-second side, fourth edge;

[0082] D3L2-third side, second edge; D3L3-third side, third edge; D3L4-third side, fourth edge;

[0083] D4L2-the second side of the fourth surface; D4L3-the third side of the fourth surface; D4L4-the fourth side of the fourth surface;

[0084] D5L1-first side of the fifth surface; D5L2-second side of the fifth surface; D5L4-fourth side of the fifth surface;

[0085] D6L1-first side of the sixth surface; D6L2-second side of the sixth surface; D6L4-fourth side of the sixth surface;

[0086] D7L1-the first side of the seventh surface; D7L2-the second side of the seventh surface; D7L4-the fourth side of the seventh surface;

[0087] D8L1-first side of the eighth surface; D8L2-second side of the eighth surface; D8L4-fourth side of the eighth surface; DETAILED DESCRIPTION

[0088] The present invention will be further described in detail below in conjunction with the accompanying drawings and specific embodiments. It should be understood that the specific embodiments described herein are only used to explain the present invention and are not used to limit the present invention.

[0089] Embodiment 1

[0090] like Figure 1-1As shown, the structure shown in the figure is a component composition and a plane unfolding diagram of a foldable tubular structure composed of four spherical connecting rod mechanisms provided by this embodiment. It includes 8 faces, namely the first face A1, the second face A2, the third face A3, the fourth face A4, the fifth face A5, the sixth face A6, the seventh face A7, and the eighth face A8, wherein the first face A1 and the third face A3 are the same parallelogram, the second face A2 and the fourth face A4 are the same parallelogram, the fifth face A5 and the seventh face A7 are the same parallelogram, and the sixth face A6 and the eighth face A8 are the same parallelogram. The length of the third side A1L3 of the first face is not equal to the length of the third side A2L3 of the second face.

[0091] The second side A1L2 of the first surface is adjacent to the fourth side A2L4 of the second surface and connected to each other through the first rotation pair M1. The first surface A1 can rotate along the axis of the first rotation pair M1 in the folding direction of the tubular structure until it overlaps with the second surface A2; the second side A2L2 of the second surface is adjacent to the fourth side A3L4 of the third surface and connected to each other through the second rotation pair M2. The second surface A2 can rotate along the axis of the second rotation pair M2 in the folding direction of the tubular structure until it is coplanar with the third surface A3; the second side A3L2 of the third surface is adjacent to the fourth side A4L4 of the fourth surface and connected to each other through the third rotation pair M3. The third surface A3 can rotate along the axis of the third rotation pair M3 in the folding direction of the tubular structure until it overlaps with the fourth surface A4; The fourth side A1L4 of the first face is adjacent to the second side A4L2 of the fourth face and are connected to each other through the fourth rotation pair M4. The first face A1 can rotate along the axis of the fourth rotation pair M4 in the folding direction of the tubular structure until it is coplanar with the fourth face A4; the second side A5L2 of the fifth face is adjacent to the fourth side A6L4 of the sixth face and are connected to each other through the fifth rotation pair M5. The fifth face A5 can rotate along the axis of the fifth rotation pair M5 in the folding direction of the tubular structure until it overlaps with the sixth face A6; the second side A6L2 of the sixth face is adjacent to the fourth side A7L4 of the seventh face and are connected to each other through the sixth rotation pair M6. The sixth face A6 can rotate along the axis of the sixth rotation pair M6 in the folding direction of the tubular structure until it is coplanar with the seventh face A7; The side A7L2 is adjacent to the fourth side A8L4 of the eighth side and is connected to each other through the seventh rotation pair M7. The seventh side A7 can rotate along the axis of the seventh rotation pair M7 in the folding direction of the tubular structure until it overlaps with the eighth side A8; the fourth side A5L4 of the fifth side is adjacent to the second side A8L2 of the eighth side and is connected to each other through the eighth rotation pair M8. The fifth side A5 can rotate along the axis of the eighth rotation pair M8 in the folding direction of the tubular structure until it is coplanar with the eighth side A8; the third side A1L3 of the first side is adjacent to the first side A5L1 of the fifth side and is connected to each other through the ninth rotation pair M9. The first side A1 can rotate along the axis of the ninth rotation pair M9 in the folding direction of the tubular structure until it overlaps with the fifth side A5; the third side A1L4 of the second side 2L3 is adjacent to the first edge A6L1 of the sixth surface and are connected to each other through the tenth rotation pair M10. The second surface A2 can rotate along the axis of the tenth rotation pair M10 along the folding direction of the tubular structure until it overlaps with the sixth surface A6; the third edge A3L3 of the third surface is adjacent to the first edge A7L1 of the seventh surface and are connected to each other through the eleventh rotation pair M11. The third surface A3 can rotate along the axis of the eleventh rotation pair M11 along the folding direction of the tubular structure until it overlaps with the seventh surface A7; the third edge A4L3 of the fourth surface is adjacent to the first edge A8L1 of the eighth surface and are connected to each other through the twelfth rotation pair M12. The fourth surface A4 can rotate along the axis of the twelfth rotation pair M12 along the folding direction of the tubular structure until it overlaps with the eighth surface A8.

[0092] The axes of the first rotational pair M1, the second rotational pair M2, the third rotational pair M3 and the fourth rotational pair M4 are parallel to each other; the axes of the fifth rotational pair M5, the sixth rotational pair M6, the seventh rotational pair M7 and the eighth rotational pair M8 are parallel to each other.

[0093] The first surface A1, the second surface A2, the sixth surface A6, and the fifth surface A5 are connected head to tail by the first rotational pair M1, the tenth rotational pair M10, the fifth rotational pair M5, and the ninth rotational pair M9 to form a first spherical four-bar linkage mechanism; the second surface A2, the third surface A3, the seventh surface A7, and the sixth surface A6 are connected head to tail by the second rotational pair M2, the eleventh rotational pair M11, the sixth rotational pair M6, and the tenth rotational pair M10 to form a second spherical four-bar linkage mechanism; the third surface A4, the fourth surface A4, the eighth surface A8, and the seventh surface A7 are connected head to tail by the third rotational pair M3, the twelfth rotational pair M12, the seventh rotational pair M7, and the eleventh rotational pair M11 to form a third spherical four-bar linkage mechanism; the fourth surface A4, the first surface A1, the fifth surface A5, and the eighth surface A8 are connected head to tail by the fourth rotational pair M4, the ninth rotational pair M9, the eighth rotational pair M8, and the twelfth rotational pair M12 to form a fourth spherical four-bar linkage mechanism.

[0094] The sum of the third angle A1K3 of the first face and the first angle A6K1 of the sixth face is 180°, the sum of the fourth angle A2K4 of the second face and the second angle A5K2 of the fifth face is 180°, the sum of the third angle A3K3 of the third face and the first angle A8K1 of the eighth face is 180°, and the sum of the fourth angle A4K4 of the fourth face and the second angle A7K2 of the seventh face is 180°.

[0095] The tenth rotational pair M10 shared by the first spherical four-bar linkage and the second spherical four-bar linkage, the eleventh rotational pair M11 shared by the second spherical four-bar linkage and the third spherical four-bar linkage, the twelfth rotational pair M12 shared by the third spherical four-bar linkage and the fourth spherical four-bar linkage, and the ninth rotational pair M9 shared by the first spherical four-bar linkage and the fourth spherical four-bar linkage.

[0096] The folding and unfolding of the structure as a whole are performed around the ninth rotation pair M9, the tenth rotation pair M10, the eleventh rotation pair M11 and the twelfth rotation pair M12. When folding, the first surface A1 and the fifth surface A5 rotate around the ninth rotation pair M9 and the angle between the two surfaces gradually decreases, the second surface A2 and the sixth surface A6 rotate around the tenth rotation pair M10 and the angle between the two surfaces gradually decreases, the third surface A3 and the seventh surface A7 rotate around the eleventh rotation pair M11 and the angle between the two surfaces gradually decreases, and the fourth surface A4 and the eighth surface A8 rotate around the twelfth rotation pair M12 and the angle between the two surfaces gradually decreases.

[0097] According to the connection mode and rotation direction of the above-mentioned surfaces, the unfolded state is a plane structure, such as Figure 1-2 As shown, it can be folded into a flat structure, such as Figure 1-3 The folding process and sequence are as shown in Figure 1-4 to Figure 1-7 As shown, Figure 1-4 Indicates the fully expanded state. Figure 1-5 and Figure 1-6 Indicates the intermediate state of folding, Figure 1-7 Indicates a fully folded state. Taking the tubular structure as the basic unit, the tubular structure is arranged and extended in the axial direction according to the above arrangement and connection method to obtain a tubular structure containing multiple basic units, such as Figure 1-8 shown.

[0098] It can be seen that as long as the above-mentioned tubular structure meets the above-mentioned constraints, that is, as long as the connection mode of the rotating pair is met, the folding and unfolding effect required by the present invention can be achieved, and its structural form and folding and unfolding mode are not affected by the specific structure of the folding unit. The rotating pair is a hinge, a hinge or a bearing; the length of the rotating pair is not limited, and it only needs to constitute a rotating pair. The component surface of each unit is a plane, a curved surface, or a surface spliced ​​by several surfaces; a cavity of any shape is provided on the component surface of each unit according to requirements. The outer contour line of each unit is a straight line, a curve or a broken line. The foldable tubular structure of the present invention is a structure without bifurcation during the movement process, and the degree of freedom is 1. A single drive can be set to complete the folding and unfolding of the foldable tubular structure. Since the tubular structure proposed by the present invention has a single degree of freedom and a simple unit structure, it has the advantages of simple installation, convenient operation, and easy transportation, and is particularly suitable for application in packaging, storage, civil engineering, aerospace and other fields.

[0099] Embodiment 2

[0100] like Figure 2-1 As shown in the figure, the structure shown in the figure is a component composition and plane development diagram of a foldable tubular structure composed of four spherical connecting rod mechanisms provided by this embodiment. It includes 8 faces, namely the first face B1, the second face B2, the third face B3, the fourth face B4, the fifth face B5, the sixth face B6, the seventh face B7, and the eighth face B8, wherein the first face B1, the fourth face B4, the sixth face B6, and the seventh face B7 are the same parallelogram, and the second face B1, the third face B3, the fifth face B5, and the eighth face B8 are the same parallelogram. The length of the third side B1L3 of the first face is equal to the length of the third side B2L3 of the second face.

[0101] The second side B1L2 of the first surface is adjacent to the fourth side B2L4 of the second surface and connected to each other through the first rotation pair N1. The first surface B1 can rotate along the axis of the first rotation pair N1 in the folding direction of the tubular structure until it overlaps with the second surface B2; the second side B2L2 of the second surface is adjacent to the fourth side B3L4 of the third surface and connected to each other through the second rotation pair N2. The second surface B2 can rotate along the axis of the second rotation pair N2 in the folding direction of the tubular structure until it is coplanar with the third surface B3; the second side B3L2 of the third surface is adjacent to the fourth side B4L4 of the fourth surface and connected to each other through the third rotation pair N3. The third surface B3 can rotate along the axis of the third rotation pair N3 in the folding direction of the tubular structure until it overlaps with the fourth surface B4; The fourth side B1L4 of the first face is adjacent to the second side B4L2 of the fourth face and connected to each other through the fourth rotation pair N4. The first face B1 can rotate along the axis of the fourth rotation pair N4 in the folding direction of the tubular structure until it is coplanar with the fourth face B4; the second side B5L2 of the fifth face is adjacent to the fourth side B6L4 of the sixth face and connected to each other through the fifth rotation pair N5. The fifth face B5 can rotate along the axis of the fifth rotation pair N5 in the folding direction of the tubular structure until it overlaps with the sixth face B6; the second side B6L2 of the sixth face is adjacent to the fourth side B7L4 of the seventh face and connected to each other through the sixth rotation pair N6. The sixth face B6 can rotate along the axis of the sixth rotation pair N6 in the folding direction of the tubular structure until it is coplanar with the seventh face B7; the second side B5L2 of the seventh face is adjacent to the fourth side B6L4 of the sixth face and connected to each other through the sixth rotation pair N6. The sixth face B6 can rotate along the axis of the sixth rotation pair N6 in the folding direction of the tubular structure until it is coplanar with the seventh face B7; The side B7L2 is adjacent to the fourth side B8L4 of the eighth side and is connected to each other through the seventh rotation pair N7. The seventh side B7 can rotate along the axis of the seventh rotation pair N7 in the folding direction of the tubular structure until it overlaps with the eighth side B8; the fourth side B5L4 of the fifth side is adjacent to the second side B8L2 of the eighth side and is connected to each other through the eighth rotation pair N8. The fifth side B5 can rotate along the axis of the eighth rotation pair N8 in the folding direction of the tubular structure until it is coplanar with the eighth side B8; the third side B1L3 of the first side is adjacent to the first side B5L1 of the fifth side and is connected to each other through the ninth rotation pair N9. The first side B1 can rotate along the axis of the ninth rotation pair N9 in the folding direction of the tubular structure until it overlaps with the fifth side B5; the third side B1L3 of the second side is adjacent to the first side B5L1 of the fifth side and is connected to each other through the ninth rotation pair N9. The first side B1 can rotate along the axis of the ninth rotation pair N9 in the folding direction of the tubular structure until it overlaps with the fifth side B5; 2L3 is adjacent to the first edge B6L1 of the sixth surface and are connected to each other through the tenth rotation pair N10. The second surface B2 can rotate along the axis of the tenth rotation pair N10 in the folding direction of the tubular structure until it overlaps with the sixth surface B6; the third edge B3L3 of the third surface is adjacent to the first edge B7L1 of the seventh surface and are connected to each other through the eleventh rotation pair N11. The third surface B3 can rotate along the axis of the eleventh rotation pair N11 in the folding direction of the tubular structure until it overlaps with the seventh surface B7; the third edge B4L3 of the fourth surface is adjacent to the first edge B8L1 of the eighth surface and are connected to each other through the twelfth rotation pair N12. The fourth surface B4 can rotate along the axis of the twelfth rotation pair N12 in the folding direction of the tubular structure until it overlaps with the eighth surface B8.

[0102] The axes of the first rotational pair N1, the second rotational pair N2, the third rotational pair N3 and the fourth rotational pair N4 are parallel to each other; the axes of the fifth rotational pair N5, the sixth rotational pair N6, the seventh rotational pair N7 and the eighth rotational pair N8 are parallel to each other.

[0103] The first surface B1, the second surface B2, the sixth surface B6, and the fifth surface B5 are connected end to end by the first rotational pair N1, the tenth rotational pair N10, the fifth rotational pair N5, and the ninth rotational pair N9 to form a first spherical four-bar linkage; the second surface B2, the third surface B3, the seventh surface B7, and the sixth surface B6 are connected end to end by the second rotational pair N2, the eleventh rotational pair N11, the sixth rotational pair N6, and the tenth rotational pair N10 to form a second spherical four-bar linkage; the third surface B4, the fourth surface B4, the eighth surface B8, and the seventh surface B7 are connected end to end by the third rotational pair N3, the twelfth rotational pair N12, the seventh rotational pair N7, and the eleventh rotational pair N11 to form a third spherical four-bar linkage; the fourth surface B4, the first surface B1, the fifth surface B5, and the eighth surface B8 are connected end to end by the fourth rotational pair N4, the ninth rotational pair N9, the eighth rotational pair N8, and the twelfth rotational pair N12 to form a fourth spherical four-bar linkage.

[0104] The sum of the third angle B1K3 of the first face and the first angle B6K1 of the sixth face is 180°, the sum of the fourth angle B2K4 of the second face and the second angle B5K2 of the fifth face is 180°, the sum of the third angle B3K3 of the third face and the first angle B8K1 of the eighth face is 180°, and the sum of the fourth angle B4K4 of the fourth face and the second angle B7K2 of the seventh face is 180°.

[0105] The tenth rotational pair N10 shared by the first spherical four-bar linkage and the second spherical four-bar linkage, the eleventh rotational pair N11 shared by the second spherical four-bar linkage and the third spherical four-bar linkage, the twelfth rotational pair N12 shared by the third spherical four-bar linkage and the fourth spherical four-bar linkage, and the ninth rotational pair N9 shared by the first spherical four-bar linkage and the fourth spherical four-bar linkage.

[0106] The folding and unfolding of the structure as a whole are performed around the ninth rotation pair N9, the tenth rotation pair N10, the eleventh rotation pair N11 and the twelfth rotation pair N12. When folding, the first surface B1 and the fifth surface B5 rotate around the ninth rotation pair N9 and the angle between the two surfaces gradually decreases, the second surface B2 and the sixth surface B6 rotate around the tenth rotation pair N10 and the angle between the two surfaces gradually decreases, the third surface B3 and the seventh surface B7 rotate around the eleventh rotation pair N11 and the angle between the two surfaces gradually decreases, and the fourth surface B4 and the eighth surface B8 rotate around the twelfth rotation pair N12 and the angle between the two surfaces gradually decreases.

[0107] According to the connection method and rotation direction of the above-mentioned surfaces, the unfolded state is a planar octagonal structure, such as Figure 2-2 As shown, it can be folded into a flat structure, such as Figure 2-3 The folding process and sequence are as shown in Figure 2-4 to Figure 2-7 As shown, Figure 2-4 Indicates the fully expanded state. Figure 2-5 and Figure 2-6 Indicates the intermediate state of folding, Figure 2-7 Indicates a fully folded state. Taking the tubular structure as the basic unit, the tubular structure is arranged and extended in the axial direction according to the above arrangement and connection method to obtain a tubular structure containing multiple basic units, such as Figure 2-8 shown.

[0108] It can be seen that as long as the above-mentioned tubular structure meets the above-mentioned constraints, that is, as long as the connection mode of the rotating pair is met, the folding and unfolding effect required by the present invention can be achieved, and its structural form and folding and unfolding mode are not affected by the specific structure of the folding unit. The rotating pair is a hinge, a hinge or a bearing; the length of the rotating pair is not limited, and it only needs to constitute a rotating pair. The component surface of each unit is a plane, a curved surface, or a surface spliced ​​by several surfaces; a cavity of any shape is provided on the component surface of each unit according to requirements. The outer contour line of each unit is a straight line, a curve or a broken line. The foldable tubular structure of the present invention is a structure without bifurcation during the movement process, and the degree of freedom is 1. A single drive can be set to complete the folding and unfolding of the foldable tubular structure. Since the tubular structure proposed by the present invention has a single degree of freedom and a simple unit structure, it has the advantages of simple installation, convenient operation, and easy transportation, and is particularly suitable for application in packaging, storage, civil engineering, aerospace and other fields.

[0109] Embodiment 3

[0110] like Figure 3-1 As shown in the figure, the structure shown in the figure is a component composition and a plane development diagram of a foldable tubular structure composed of four spherical connecting rod mechanisms provided by this embodiment. It includes 8 faces, namely the first face C1, the second face C2, the third face C3, the fourth face C4, the fifth face C5, the sixth face C6, the seventh face C7, and the eighth face C8, wherein the first face C1 and the sixth face C6 are the same parallelogram, the second face C2 and the fifth face C5 are the same parallelogram, the third face C3 and the eighth face C8 are the same parallelogram, and the fourth face C4 and the seventh face C7 are the same parallelogram.

[0111] The second side C1L2 of the first surface is adjacent to the fourth side C2L4 of the second surface and connected to each other through the first rotation pair P1. The first surface C1 can rotate along the axis of the first rotation pair P1 in the folding direction of the tubular structure until it overlaps with the second surface C2; ​​the second side C2L2 of the second surface is adjacent to the fourth side C3L4 of the third surface and connected to each other through the second rotation pair P2. The second surface C2 can rotate along the axis of the second rotation pair P2 in the folding direction of the tubular structure until it is coplanar with the third surface C3; the second side C3L2 of the third surface is adjacent to the fourth side C4L4 of the fourth surface and connected to each other through the third rotation pair P3. The third surface C3 can rotate along the axis of the third rotation pair P3 in the folding direction of the tubular structure until it overlaps with the fourth surface C4; The fourth side C1L4 of the first surface is adjacent to the second side C4L2 of the fourth surface and is connected to each other through the fourth rotation pair P4. The first surface C1 can rotate along the axis of the fourth rotation pair P4 in the folding direction of the tubular structure until it is coplanar with the fourth surface C4; the second side C5L2 of the fifth surface is adjacent to the fourth side C6L4 of the sixth surface and is connected to each other through the fifth rotation pair P5. The fifth surface C5 can rotate along the axis of the fifth rotation pair P5 in the folding direction of the tubular structure until it overlaps with the sixth surface C6; the second side C6L2 of the sixth surface is adjacent to the fourth side C7L4 of the seventh surface and is connected to each other through the sixth rotation pair P6. The sixth surface C6 can rotate along the axis of the sixth rotation pair P6 in the folding direction of the tubular structure until it is coplanar with the seventh surface C7; the second side C6L2 of the seventh surface is adjacent to the fourth side C7L4 of the seventh surface and is connected to each other through the sixth rotation pair P6. The sixth surface C6 can rotate along the axis of the sixth rotation pair P6 in the folding direction of the tubular structure until it is coplanar with the seventh surface C7; The edge C7L2 is adjacent to the fourth edge C8L4 of the eighth surface and is connected to each other through the seventh rotation pair P7. The seventh surface C7 can rotate along the axis of the seventh rotation pair P7 in the folding direction of the tubular structure until it overlaps with the eighth surface C8; the fourth edge C5L4 of the fifth surface is adjacent to the second edge C8L2 of the eighth surface and is connected to each other through the eighth rotation pair P8. The fifth surface C5 can rotate along the axis of the eighth rotation pair P8 in the folding direction of the tubular structure until it is coplanar with the eighth surface C8; the third edge C1L3 of the first surface is adjacent to the first edge C5L1 of the fifth surface and is connected to each other through the ninth rotation pair P9. The first surface C1 can rotate along the axis of the ninth rotation pair P9 in the folding direction of the tubular structure until it overlaps with the fifth surface C5; the third edge C 2L3 is adjacent to the first edge C6L1 of the sixth surface and is connected to each other through the tenth rotation pair P10. The second surface C2 can rotate along the axis of the tenth rotation pair P10 in the folding direction of the tubular structure until it overlaps with the sixth surface C6; the third edge C3L3 of the third surface is adjacent to the first edge C7L1 of the seventh surface and is connected to each other through the eleventh rotation pair P11. The third surface C3 can rotate along the axis of the eleventh rotation pair P11 in the folding direction of the tubular structure until it overlaps with the seventh surface C7; the third edge C4L3 of the fourth surface is adjacent to the first edge C8L1 of the eighth surface and is connected to each other through the twelfth rotation pair P12. The fourth surface C4 can rotate along the axis of the twelfth rotation pair P12 in the folding direction of the tubular structure until it overlaps with the eighth surface C8.

[0112] The axis of the first rotational pair P1, the axis of the second rotational pair P2, the axis of the third rotational pair P3, and the axis of the fourth rotational pair P4 are parallel to each other; the axis of the fifth rotational pair P5, the axis of the sixth rotational pair P6, the axis of the seventh rotational pair P7, and the axis of the eighth rotational pair P8 are parallel to each other.

[0113] The first surface C1, the second surface C2, the sixth surface C6, and the fifth surface C5 are connected head to tail by the first rotational pair P1, the tenth rotational pair P10, the fifth rotational pair P5, and the ninth rotational pair P9 to form a first spherical four-bar linkage; the second surface C2, the third surface C3, the seventh surface C7, and the sixth surface C6 are connected head to tail by the second rotational pair P2, the eleventh rotational pair P11, the sixth rotational pair P6, and the tenth rotational pair P10 to form a second spherical four-bar linkage; the third surface C4, the fourth surface C4, the eighth surface C8, and the seventh surface C7 are connected head to tail by the third rotational pair P3, the twelfth rotational pair P12, the seventh rotational pair P7, and the eleventh rotational pair P11 to form a third spherical four-bar linkage; the fourth surface C4, the first surface C1, the fifth surface C5, and the eighth surface C8 are connected head to tail by the fourth rotational pair P4, the ninth rotational pair P9, the eighth rotational pair P8, and the twelfth rotational pair P12 to form a fourth spherical four-bar linkage.

[0114] The sum of the third angle C1K3 of the first face and the first angle C6K1 of the sixth face is 180°, the sum of the fourth angle C2K4 of the second face and the second angle C5K2 of the fifth face is 180°, the sum of the third angle C3K3 of the third face and the first angle C8K1 of the eighth face is 180°, and the sum of the fourth angle C4K4 of the fourth face and the second angle C7K2 of the seventh face is 180°.

[0115] The tenth rotational pair P10 shared by the first spherical four-bar linkage and the second spherical four-bar linkage, the eleventh rotational pair P11 shared by the second spherical four-bar linkage and the third spherical four-bar linkage, the twelfth rotational pair P12 shared by the third spherical four-bar linkage and the fourth spherical four-bar linkage, and the ninth rotational pair P9 shared by the first spherical four-bar linkage and the fourth spherical four-bar linkage.

[0116] The folding and unfolding of the structure as a whole are performed around the ninth rotation pair P9, the tenth rotation pair P10, the eleventh rotation pair P11 and the twelfth rotation pair P12. When folding, the first surface C1 and the fifth surface C5 rotate around the ninth rotation pair P9 and the angle between the two surfaces gradually decreases, the second surface C2 and the sixth surface C6 rotate around the tenth rotation pair P10 and the angle between the two surfaces gradually decreases, the third surface C3 and the seventh surface C7 rotate around the eleventh rotation pair P11 and the angle between the two surfaces gradually decreases, and the fourth surface C4 and the eighth surface C8 rotate around the twelfth rotation pair P12 and the angle between the two surfaces gradually decreases.

[0117] According to the connection method and rotation direction of the above-mentioned surfaces, the unfolded state is a tubular structure with a triangular cross section, such as Figure 3-2 As shown, it can be folded into a flat structure, such as Figure 3-3 The folding process and sequence are as shown in Figure 3-4 to Figure 3-7 As shown, Figure 3-4 Indicates the fully expanded state. Figure 3-5 and Figure 3-6 Indicates the intermediate state of folding, Figure 3-7 Indicates a fully folded state. Taking the tubular structure as the basic unit, the tubular structure is arranged and extended in the axial direction according to the above arrangement and connection method to obtain a tubular structure containing multiple basic units, such as Figure 3-8 shown.

[0118] It can be seen that as long as the above-mentioned tubular structure meets the above-mentioned constraints, that is, as long as the connection mode of the rotating pair is met, the folding and unfolding effect required by the present invention can be achieved, and its structural form and folding and unfolding mode are not affected by the specific structure of the folding unit. The rotating pair is a hinge, a hinge or a bearing; the length of the rotating pair is not limited, and it only needs to constitute a rotating pair. The component surface of each unit is a plane, a curved surface, or a surface spliced ​​by several surfaces; a cavity of any shape is provided on the component surface of each unit according to requirements. The outer contour line of each unit is a straight line, a curve or a broken line. The foldable tubular structure of the present invention is a structure without bifurcation during the movement process, and the degree of freedom is 1. A single drive can be set to complete the folding and unfolding of the foldable tubular structure. Since the tubular structure proposed by the present invention has a single degree of freedom and a simple unit structure, it has the advantages of simple installation, convenient operation, and easy transportation, and is particularly suitable for application in packaging, storage, civil engineering, aerospace and other fields.

[0119] Embodiment 4

[0120] like Figure 4-1 As shown in the figure, the structure shown in the figure is a component composition and a plane development diagram of a foldable tubular structure composed of four spherical connecting rod mechanisms provided by this embodiment. It includes 8 faces, namely the first face D1, the second face D2, the third face D3, the fourth face D4, the fifth face D5, the sixth face D6, the seventh face D7, and the eighth face D8, wherein the first face D1 and the fourth face D4 are the same trapezoid, the second face D2 and the third face D3 are the same trapezoid, the fifth face D5 and the eighth face D8 are the same trapezoid, and the sixth face D6 and the seventh face D7 are the same trapezoid.

[0121] The second side D1L2 of the first surface is adjacent to the fourth side D2L4 of the second surface and is connected to each other through the first rotation pair Q1. The first surface D1 can rotate along the axis of the first rotation pair Q1 in the folding direction of the tubular structure until it overlaps with the second surface D2; the second side D2L2 of the second surface is adjacent to the fourth side D3L4 of the third surface and is connected to each other through the second rotation pair Q2. The second surface D2 can rotate along the axis of the second rotation pair Q2 in the folding direction of the tubular structure until it is coplanar with the third surface D3; the second side D3L2 of the third surface is adjacent to the fourth side D4L4 of the fourth surface and is connected to each other through the third rotation pair Q3. The third surface D3 can rotate along the axis of the third rotation pair Q3 in the folding direction of the tubular structure until it overlaps with the fourth surface D4; The fourth side D1L4 of the first surface is adjacent to the second side D4L2 of the fourth surface and is connected to each other through the fourth rotation pair Q4. The first surface D1 can rotate along the axis of the fourth rotation pair Q4 in the folding direction of the tubular structure until it is coplanar with the fourth surface D4. The second side D5L2 of the fifth surface is adjacent to the fourth side D6L4 of the sixth surface and is connected to each other through the fifth rotation pair Q5. The fifth surface D5 can rotate along the axis of the fifth rotation pair Q5 in the folding direction of the tubular structure until it overlaps with the sixth surface D6. The second side D6L2 of the sixth surface is adjacent to the fourth side D7L4 of the seventh surface and is connected to each other through the sixth rotation pair Q6. The sixth surface D6 can rotate along the axis of the sixth rotation pair Q6 in the folding direction of the tubular structure until it is coplanar with the seventh surface D7. The side D7L2 is adjacent to the fourth side D8L4 of the eighth side and is connected to each other through the seventh rotation pair Q7. The seventh side D7 can be rotated along the axis of the seventh rotation pair Q7 in the folding direction of the tubular structure until it overlaps with the eighth side D8; the fourth side D5L4 of the fifth side is adjacent to the second side D8L2 of the eighth side and is connected to each other through the eighth rotation pair Q8. The fifth side D5 can be rotated along the axis of the eighth rotation pair Q8 in the folding direction of the tubular structure until it is coplanar with the eighth side D8; the third side D1L3 of the first side is adjacent to the first side D5L1 of the fifth side and is connected to each other through the ninth rotation pair Q9. The first side D1 can be rotated along the axis of the ninth rotation pair Q9 in the folding direction of the tubular structure until it overlaps with the fifth side D5; the third side D 2L3 is adjacent to the first edge D6L1 of the sixth surface and is connected to each other through the tenth rotation pair Q10. The second surface D2 can rotate along the axis of the tenth rotation pair Q10 in the folding direction of the tubular structure until it overlaps with the sixth surface D6; the third edge D3L3 of the third surface is adjacent to the first edge D7L1 of the seventh surface and is connected to each other through the eleventh rotation pair Q11. The third surface D3 can rotate along the axis of the eleventh rotation pair Q11 in the folding direction of the tubular structure until it overlaps with the seventh surface D7; the third edge D4L3 of the fourth surface is adjacent to the first edge D8L1 of the eighth surface and is connected to each other through the twelfth rotation pair Q12. The fourth surface D4 can rotate along the axis of the twelfth rotation pair Q12 in the folding direction of the tubular structure until it overlaps with the eighth surface D8.

[0122] The axes of the first rotating pair Q1, the second rotating pair Q2, the third rotating pair Q3 and the fourth rotating pair Q4 are parallel to each other; the axes of the fifth rotating pair Q5, the sixth rotating pair Q6, the seventh rotating pair Q7 and the eighth rotating pair Q8 are parallel to each other.

[0123] The first surface D1, the second surface D2, the sixth surface D6, and the fifth surface D5 are connected head to tail by the first rotational pair Q1, the tenth rotational pair Q10, the fifth rotational pair Q5, and the ninth rotational pair Q9 to form a first spherical four-bar linkage; the second surface D2, the third surface D3, the seventh surface D7, and the sixth surface D6 are connected head to tail by the second rotational pair Q2, the eleventh rotational pair Q11, the sixth rotational pair Q6, and the tenth rotational pair Q10 to form a second spherical four-bar linkage; the third surface D4, the fourth surface D4, the eighth surface D8, and the seventh surface D7 are connected head to tail by the third rotational pair Q3, the twelfth rotational pair Q12, the seventh rotational pair Q7, and the eleventh rotational pair Q11 to form a third spherical four-bar linkage; the fourth surface D4, the first surface D1, the fifth surface D5, and the eighth surface D8 are connected head to tail by the fourth rotational pair Q4, the ninth rotational pair Q9, the eighth rotational pair Q8, and the twelfth rotational pair Q12 to form a fourth spherical four-bar linkage.

[0124] The sum of the third angle D1K3 of the first face and the first angle D6K1 of the sixth face is 180°, the sum of the fourth angle D2K4 of the second face and the second angle D5K2 of the fifth face is 180°, the sum of the third angle D3K3 of the third face and the first angle D8K1 of the eighth face is 180°, and the sum of the fourth angle D4K4 of the fourth face and the second angle D7K2 of the seventh face is 180°.

[0125] The tenth rotation pair Q10 is shared by the first spherical four-bar linkage and the second spherical four-bar linkage, the eleventh rotation pair Q11 is shared by the second spherical four-bar linkage and the third spherical four-bar linkage, the twelfth rotation pair Q12 is shared by the third spherical four-bar linkage and the fourth spherical four-bar linkage, and the ninth rotation pair Q9 is shared by the first spherical four-bar linkage and the fourth spherical four-bar linkage.

[0126] The folding and unfolding of the structure as a whole are performed around the ninth rotation pair Q9, the tenth rotation pair Q10, the eleventh rotation pair Q11 and the twelfth rotation pair Q12. When folding, the first surface D1 and the fifth surface D5 rotate around the ninth rotation pair Q9 and the angle between the two surfaces gradually decreases, the second surface D2 and the sixth surface D6 rotate around the tenth rotation pair Q10 and the angle between the two surfaces gradually decreases, the third surface D3 and the seventh surface D7 rotate around the eleventh rotation pair Q11 and the angle between the two surfaces gradually decreases, and the fourth surface D4 and the eighth surface D8 rotate around the twelfth rotation pair Q12 and the angle between the two surfaces gradually decreases.

[0127] According to the connection method and rotation direction of the above-mentioned surfaces, the unfolded state is a planar octagonal structure, such as Figure 4-2 As shown, it can be folded into a flat structure, such as Figure 4-3 The folding process and sequence are as shown in Figure 4-4 to Figure 4-7 As shown, Figure 4-4 Indicates the fully expanded state. Figure 4-5 and Figure 4-6 Indicates the intermediate state of folding, Figure 4-7 Indicates a fully folded state. Taking the tubular structure as the basic unit, the tubular structure is arranged and extended in the axial direction according to the above arrangement and connection method to obtain a tubular structure containing multiple basic units, such as Figure 4-8 shown.

[0128] It can be seen that as long as the above-mentioned tubular structure meets the above-mentioned constraints, that is, as long as the connection mode of the rotating pair is met, the folding and unfolding effect required by the present invention can be achieved, and its structural form and folding and unfolding mode are not affected by the specific structure of the folding unit. The rotating pair is a hinge, a hinge or a bearing; the length of the rotating pair is not limited, and it only needs to constitute a rotating pair. The component surface of each unit is a plane, a curved surface, or a surface spliced ​​by several surfaces; a cavity of any shape is provided on the component surface of each unit according to requirements. The outer contour line of each unit is a straight line, a curve or a broken line. The foldable tubular structure of the present invention is a structure without bifurcation during the movement process, and the degree of freedom is 1. A single drive can be set to complete the folding and unfolding of the foldable tubular structure. Since the tubular structure proposed by the present invention has a single degree of freedom and a simple unit structure, it has the advantages of simple installation, convenient operation, and easy transportation, and is particularly suitable for application in packaging, storage, civil engineering, aerospace and other fields.

[0129] Finally, it should be pointed out that the above examples are only used to illustrate the calculation process of the present invention, rather than to limit it. Although the present invention has been described in detail with reference to the above examples, a person skilled in the art should understand that the calculation process described in the above examples can still be modified, or some parameters can be replaced by equivalents, and these modifications or replacements do not make the essence of the corresponding calculation method deviate from the spirit and scope of the calculation method of the present invention.

[0130] The present invention is not limited to the embodiments described above. The above description of the specific embodiments is intended to describe and illustrate the technical solution of the present invention. The above specific embodiments are merely illustrative and not restrictive. Without departing from the scope of the present invention and the scope of protection of the claims, a person of ordinary skill in the art can also make many forms of specific changes under the guidance of the present invention, which all fall within the scope of protection of the present invention.

Claims

1. A single-degree-of-freedom foldable tubular structure based on four spherical four-bar linkages, characterized in that: The invention comprises eight faces, namely, a first face, a second face, a third face, a fourth face, a fifth face, a sixth face, a seventh face, and an eighth face; the first face, the second face, the third face, and the fourth face are connected end to end in sequence to form a first prism, the fifth face, the sixth face, the seventh face, and the eighth face are connected end to end in sequence to form a second prism, and the second prism is arranged below the first prism; the four sides at the top of the second prism are connected to the four sides at the bottom of the first prism to form a spatial quadrilateral; The second side of the first surface is adjacent to the fourth side of the second surface and connected to each other through the first rotation pair; the second side of the second surface is adjacent to the fourth side of the third surface and connected to each other through the second rotation pair; the second side of the third surface is adjacent to the fourth side of the fourth surface and connected to each other through the third rotation pair; the fourth side of the first surface is adjacent to the second side of the fourth surface and connected to each other through the fourth rotation pair; the second side of the fifth surface is adjacent to the fourth side of the sixth surface and connected to each other through the fifth rotation pair; the second side of the sixth surface is adjacent to the fourth side of the seventh surface and connected to each other through the sixth rotation pair; the second side of the seventh surface is adjacent to the fourth side of the eighth surface and connected to each other through the seventh rotation pair; the fourth side of the fifth surface is adjacent to the second side of the eighth surface and connected to each other through the eighth rotation pair; the third side of the first surface is adjacent to the first side of the fifth surface and connected to each other through the ninth rotation pair; the third side of the second surface is adjacent to the first side of the sixth surface and connected to each other through the tenth rotation pair; the third side of the third surface is adjacent to the first side of the seventh surface and connected to each other through the eleventh rotation pair; the third side of the fourth surface is adjacent to the first side of the eighth surface and connected to each other through the twelfth rotation pair; The first rotation secondary axis, the second rotation secondary axis, the third rotation secondary axis, and the fourth rotation secondary axis are parallel to each other; the fifth rotation secondary axis, the sixth rotation secondary axis, the seventh rotation secondary axis, and the eighth rotation secondary axis are parallel to each other; The first surface, the second surface, the sixth surface, and the fifth surface are connected in sequence by the first rotational pair, the tenth rotational pair, the fifth rotational pair, and the ninth rotational pair to form a first spherical four-bar linkage; the second surface, the third surface, the seventh surface, and the sixth surface are connected in sequence by the second rotational pair, the eleventh rotational pair, the sixth rotational pair, and the tenth rotational pair to form a second spherical four-bar linkage; the third surface, the fourth surface, the eighth surface, and the seventh surface are connected in sequence by the third rotational pair, the twelfth rotational pair, the seventh rotational pair, and the eleventh rotational pair to form a third spherical four-bar linkage; the fourth surface, the first surface, the fifth surface, and the eighth surface are connected in sequence by the fourth rotational pair, the ninth rotational pair, the eighth rotational pair, and the twelfth rotational pair to form a fourth spherical four-bar linkage; The first spherical four-bar linkage and the second spherical four-bar linkage share the tenth rotational pair, the second spherical four-bar linkage and the third spherical four-bar linkage share the eleventh rotational pair, the third spherical four-bar linkage and the fourth spherical four-bar linkage share the twelfth rotational pair, and the first spherical four-bar linkage and the fourth spherical four-bar linkage share the ninth rotational pair; Define the upper left corner, upper right corner, lower right corner and lower left corner in the plane unfolded view of each face to be the first angle, the second angle, the third angle and the fourth angle respectively; wherein the sum of the angles of the third angle of the first face and the first angle of the sixth face is 180°, the sum of the angles of the fourth angle of the second face and the second angle of the fifth face is 180°, the sum of the angles of the third angle of the third face and the first angle of the eighth face is 180°, and the sum of the angles of the fourth angle of the fourth face and the second angle of the seventh face is 180°; The folding and unfolding of the single-degree-of-freedom foldable tubular structure are performed around the ninth rotation pair, the tenth rotation pair, the eleventh rotation pair and the twelfth rotation pair; when folding, the first surface and the fifth surface rotate around the ninth rotation pair and the angle between the two surfaces gradually decreases, the second surface and the sixth surface rotate around the tenth rotation pair and the angle between the two surfaces gradually decreases, the third surface and the seventh surface rotate around the eleventh rotation pair and the angle between the two surfaces gradually decreases, and the fourth surface and the eighth surface rotate around the twelfth rotation pair and the angle between the two surfaces gradually decreases.

2. A single-degree-of-freedom foldable tubular structure based on four spherical four-bar linkages according to claim 1, characterized in that: Each component surface of the foldable tubular structure is a parallelogram, a trapezoid or a combination of the two.

3. A single-degree-of-freedom foldable tubular structure based on four spherical four-bar linkages according to claim 1 or 2, characterized in that: Different unfolding forms and folding forms can be achieved by changing the parameters of the foldable tubular structure, wherein the parameters include the angles of each component surface and the side lengths of the spatial quadrilateral.

4. A single-degree-of-freedom foldable tubular structure based on four spherical four-bar linkages according to claim 1 or 2, characterized in that: The mutual conversion between the spatial body structure and the spatial body structure, the plane structure and the plane structure, or the spatial body structure and the plane structure is realized by changing the included angle of the adjacent surfaces in the foldable tubular structure.

5. A single-degree-of-freedom foldable tubular structure based on four spherical four-bar linkages according to claim 1 or 2, characterized in that: The foldable tubular structure can be arranged and extended in the axial direction.

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