A Concentrically-Driven Multi-Degree-of-Freedom Space Folding and Unfolding Mechanism for a Spacecraft Solar Sail

Abstract

The present invention provides a multi-degree-of-freedom space folding and unfolding mechanism for a solar sail of a spacecraft with centralized drive, which includes a bracket, a main shaft, an end face bevel gear, a solar sail panel having multiple movable array surfaces, a plurality of drive units arranged corresponding to the movable array surfaces one by one, and a plurality of actuating units arranged corresponding to the movable array surfaces one by one. According to the folding and unfolding mechanism of the present invention, multiple pairs of bevel gears meshing with the end face bevel gear rotate in reverse coaxially, and a specially designed lead screw shaft transmits the rotational motion into the folding and unfolding motion of the solar sail array surface and the rotation around the axis, so as to realize the switching between the unfolded state and the folded state of the solar sail. The folding and unfolding mechanism of the present invention has the advantage of central symmetry, greatly reducing the dynamic load during the in-orbit service of the spacecraft; the drive source is single and centralized without redundancy, further expanding the mounting space for the effective payload of the spacecraft; it can achieve multi-degree-of-freedom motion, improving the space storage ratio of the spacecraft; the overall adopts a gear-screw drive form, with high motion accuracy.

Description

Technical Field

[0001] The present invention belongs to the technical field of spacecraft structure design, and particularly relates to a centralized drive type spacecraft solar sail multi-degree-of-freedom space folding and unfolding mechanism. Background Art

[0002] The great progress of modern space technology has increasingly promoted the development of human space exploration technology. As the main power energy collection device on spacecraft, solar sails have a profound impact on the in-orbit service performance of spacecraft. At present, due to the limited accommodation space of the launch vehicle fairing, large space folding and unfolding mechanisms are widely used in the actuation systems of spacecraft solar sails. The spacecraft space folding and unfolding mechanism effectively solves the technical problem of the limited envelope space of the launcher, and its application advantages are becoming increasingly prominent.

[0003] There are various types of solar sail space folding and unfolding mechanisms, each with different characteristics. In recent years, the application of rod-shaped truss unfolding mechanisms has developed rapidly and become the core motion mechanism of many spacecraft solar sails. Some truss unfolding mechanisms can unfold in the orthogonal direction. They are lightweight in structure but have low stiffness, and are prone to large deflection deformation under disturbance, which cannot meet the motion accuracy requirements of space mechanisms. Another type of solar sail motion mechanism adds active mechanisms mechanically to achieve multi-mode motion, resulting in a dispersed drive source and complex drive units, which also reduces the reliability of the solar sail motion mechanism. Although the research and industrialization of mechanism unfolding technology are becoming increasingly in-depth, there are still many technical problems to be solved. The current prominent problems mainly include irreversible unfolding process, multiple drive sources or redundant drive mechanisms, single degree of freedom, low motion accuracy, and poor structural symmetry.

[0004] Therefore, it is expected to have a new folding and unfolding solution for spacecraft solar sails to solve or weaken some of the above technical problems in the existing solutions. Summary of the Invention

[0005] In order to solve the technical bottlenecks existing in the spacecraft solar sail motion mechanism in the prior art, the present invention designs a centralized drive type spacecraft solar sail multi-degree-of-freedom space folding and unfolding mechanism. The main actuation principle of this mechanism is that a pair of coaxial and reversely rotating bevel gears rotate relative to each other to drive the solar sail plate to achieve multi-degree-of-freedom motion. Specifically, multiple pairs of bevel gears meshing with the active face bevel gear rotate coaxially and reversely. The specially designed lead screw shaft transmits the rotational motion to the folding and unfolding motion of the solar sail array surface and the rotation of the array surface around the axis through transmission components, so as to realize the switching between the unfolded state and the folded state of the solar sail.

[0006] The technical solution of the present invention is as follows:

[0007] A multi-degree-of-freedom space folding and unfolding mechanism for a concentrated drive spacecraft solar sail, which is characterized in that it includes a bracket, a main shaft and an end face bevel gear, and also includes a solar sail plate with multiple movable arrays, a plurality of drive units arranged corresponding to the multiple movable arrays one by one, and a plurality of actuating units arranged corresponding to the multiple movable arrays one by one;

[0008] The bracket is fixed on the spacecraft;

[0009] The main shaft is driven by an electric motor on the spacecraft;

[0010] The end face bevel gear is supported by the bracket and rotates together with the main shaft;

[0011] The drive unit includes a bevel gear, a lead screw shaft and a lead screw shaft support,

[0012] The bevel gear is sleeved on the first end of the lead screw shaft and meshes with the end face bevel gear, and the lead screw shaft support is arranged on the bracket and supports the lead screw shaft,

[0013] The lead screw shaft includes two straight grooves located at both ends of the lead screw shaft and a spiral groove located between the straight grooves, and the straight grooves are communicated with the spiral groove;

[0014] The actuating unit includes a transmission member, an excitation clutch, a universal joint, a sailboard rotating shaft, a connecting rod, a rotating shaft support, and two pressing spring switches,

[0015] The transmission member is sleeved on the lead screw shaft and has a positioning column that moves in the straight grooves and the spiral groove of the lead screw shaft. The second end of the lead screw shaft is connected to the input end of the excitation clutch, and the output end of the excitation clutch is connected to the sailboard rotating shaft via a universal joint,

[0016] The two pressing spring switches are respectively arranged at the transition parts of the two straight grooves and the spiral groove of the lead screw shaft, and the two pressing spring switches are triggered under the extrusion of the positioning column of the transmission member to independently control the closing and opening of the excitation clutch,

[0017] One end of the connecting rod is fixed to the transmission member, and the other end is hinged to the rotating shaft support so that the rotating shaft support can perform a sector sweeping motion around the axis of the main shaft,

[0018] The rotating shaft support is sleeved on the sailboard rotating shaft so that the rotating shaft support can rotate relative to the sailboard rotating shaft, and the movable array is fixed to the sailboard rotating shaft to move together with the sailboard rotating shaft, thereby realizing the switching between the unfolded state and the folded state of the movable array;

[0019] The lead screw shafts of the plurality of drive units are arranged symmetrically about the axis of the main shaft.

[0020] Further, the actuating unit further includes a spring piece, and the rotating shaft support is hinged to the connecting rod via the spring piece.

[0021] Further, the actuating unit further includes two leaf springs, which are respectively arranged at the joint positions between the two straight grooves and the helical groove of the lead screw shaft, so that the clamping post moves unidirectionally within the straight groove.

[0022] Further, the axis of the lead screw shaft is orthogonal to the axis of the main shaft.

[0023] Further, the actuating unit further includes a connecting element located between the connecting rod and the spring piece. One end of the connecting element is fixed to the spring piece, and the other end has a cylindrical portion.

[0024] The connecting rod is in a U-shaped configuration and includes a cross bar and two legs that can be disassembled and assembled. The two legs are connected to the transmission member on both sides of the transmission member.

[0025] The cylindrical portion of the connecting element is sleeved on the cross bar and can rotate relative to the cross bar.

[0026] Further, the actuating unit further includes two sleeves, which are respectively sleeved on the cross bar on both sides of the cylindrical portion.

[0027] Further, the solar sail also includes a fixed array surface, which is fixed to the bracket. When the movable array surface is in the deployed state, the fixed array surface and the movable array surface are in the same plane.

[0028] Further, the bracket is in a cage-like structure. The axis of the main shaft is consistent with the axis of the bracket. One axial end of the bracket is connected to the spacecraft, and the other axial end is connected to the face bevel gear.

[0029] The beneficial effects of the present invention are as follows:

[0030] 1. The multi-degree-of-freedom space folding and unfolding mechanism of the solar sail of the present invention has the advantage of high central symmetry. Its driving main shaft is the central inertia main shaft of the mechanism, avoiding the occurrence of additional dynamic loads during the movement of the mechanism, thereby affecting the stability of the spacecraft itself, and greatly reducing the dynamic load during the in-orbit service of the spacecraft.

[0031] 2. The multi-degree-of-freedom space folding and unfolding mechanism of the solar sail of the present invention adopts a centralized drive-distributed parallel transmission. The drive source is single and centralized without redundancy, further expanding the carrying space of the effective payload of the spacecraft.

[0032] 3. The multi-degree-of-freedom space folding and unfolding mechanism of the solar sail of the present invention can achieve multi-degree-of-freedom movement, effectively ensuring the switching between the attitude adjustment mode and the folding and unfolding mode of the sailboard. The movable array surface of the solar sail in the attitude adjustment mode can rotate around the sailboard rotating shaft to adjust the attitude, avoiding mutual interference during the movement of the solar sailboard and being disturbed, and also improving the space storage ratio of the spacecraft.

[0033] 4. The movable front surfaces of the sailboards of the multi-degree-of-freedom space folding and unfolding mechanism of the solar sail of the present invention are independently and non-crosslinked in movement, and the overall mechanism adopts a gear-screw drive form, so that the unfolding movement accuracy is high.

[0034] 5. By adopting a spring plate structure, the rigid connection between structures is greatly avoided, and the problem of movement jamming of the mechanism at the critical dead point state is also avoided, improving the functional reliability of the folding and unfolding mechanism movement. BRIEF DESCRIPTION OF THE DRAWINGS

[0035] Through the following description with reference to the drawings, the features and advantages of the present invention will become more easily understood. The drawings are not drawn to scale, and some features are enlarged or reduced to show the details of specific components. In the drawings:

[0036] Figure 1A is a three-dimensional overall structure view of the centralized drive type spacecraft solar sail multi-degree-of-freedom space folding and unfolding mechanism according to an exemplary embodiment of the present invention;

[0037] Figure 1B is a top view of the centralized drive type spacecraft solar sail multi-degree-of-freedom space folding and unfolding mechanism when the solar sailboard is in the unfolded state according to an exemplary embodiment of the present invention;

[0038] Figure 1C is a bottom view of the centralized drive type spacecraft solar sail multi-degree-of-freedom space folding and unfolding mechanism when the solar sailboard is in the unfolded state according to an exemplary embodiment of the present invention;

[0039] Figure 2 is a schematic three-dimensional view showing the movement principle of a single pair of movable front surfaces in the centralized drive type spacecraft solar sail multi-degree-of-freedom space folding and unfolding mechanism according to an exemplary embodiment of the present invention;

[0040] Figure 3 is a schematic three-dimensional view showing the working principle of the screw shaft and transmission parts in the centralized drive type spacecraft solar sail multi-degree-of-freedom space folding and unfolding mechanism according to an exemplary embodiment of the present invention;

[0041] Figure 4A is a plan view of the solar sailboard in the centralized drive type spacecraft solar sail multi-degree-of-freedom space folding and unfolding mechanism when it is in the unfolded state according to an exemplary embodiment of the present invention;

[0042] Figure 4B is a plan view of the solar sailboard in the centralized drive type spacecraft solar sail multi-degree-of-freedom space folding and unfolding mechanism when it is in the folded state according to an exemplary embodiment of the present invention;

[0043] Figure 5It is a schematic perspective view when adjusting the attitude of two symmetrical movable front surfaces in the centralized drive type spacecraft solar sail multi-degree-of-freedom space folding and unfolding mechanism according to an exemplary embodiment of the present invention at the unfolding position.

[0044] Figure 6 It is a schematic plan view showing the arrangement structure of the end face bevel gear and multiple lead screw shafts in the centralized drive type spacecraft solar sail multi-degree-of-freedom space folding and unfolding mechanism according to an exemplary embodiment of the present invention;

[0045] Figure 7 It is a schematic perspective view of the rotating shaft support, spring plate, connecting element and connecting rod in the centralized drive type spacecraft solar sail multi-degree-of-freedom space folding and unfolding mechanism according to an exemplary embodiment of the present invention;

[0046] Figure 8 It is a schematic perspective view of the bracket in the centralized drive type spacecraft solar sail multi-degree-of-freedom space folding and unfolding mechanism according to an exemplary embodiment of the present invention.

[0047] Reference numerals:

[0048] 1 - Bracket, 101 - Hole, 102 - Protrusion;

[0049] 2 - Main shaft;

[0050] 3 - End face bevel gear;

[0051] 4 - Solar sail panel, 401 - Movable front surface, 402 - Fixed front surface, 403 - Reinforcing rib;

[0052] 501 - Bevel gear, 502 - Lead screw shaft, 5021 - First end, 5022 - Second end, 5023 - Straight groove, 5024 - Helical groove, 503 - Lead screw shaft support;

[0053] 601 - Transmission part, 6011 - Card position column, 602 - Excitation clutch, 603 - Universal joint, 604 - Sail panel rotating shaft, 605 - Connecting rod, 6051 - Cross bar, 6052 - Leg, 606 - Rotating shaft support, 607 - Press spring switch, 608 - Spring plate, 609 - Leaf spring, 610 - Connecting element, 6101 - Cylindrical part, 611 - Sleeve. Detailed implementation manners

[0054] The present invention will be described in detail below with reference to the accompanying drawings by means of the exemplary embodiments of the present invention. It should be noted that the following detailed description of the present invention is only for the purpose of illustration and does not limit the present invention. In addition, the same reference numerals are used to represent the same components in the respective drawings.

[0055] First, refer to Figures 1A to 1CProvide an overall description of the centralized drive spacecraft solar sail multi-degree-of-freedom space deployment mechanism provided by the present invention. Figure 1A Is a three-dimensional overall structure diagram of the centralized drive spacecraft solar sail multi-degree-of-freedom space deployment mechanism according to an exemplary embodiment of the present invention. Figure 1B Is a top view of the centralized drive spacecraft solar sail multi-degree-of-freedom space deployment mechanism when the solar sail panel is in the deployed state according to an exemplary embodiment of the present invention. Figure 1C Is a bottom view of the centralized drive spacecraft solar sail multi-degree-of-freedom space deployment mechanism when the solar sail panel is in the deployed state according to an exemplary embodiment of the present invention.

[0056] As Figure 1A shown, the centralized drive spacecraft solar sail multi-degree-of-freedom space deployment mechanism as an exemplary embodiment of the present invention may include a bracket 1, a main shaft 2, an end face bevel gear 3, and a solar sail panel 4, where the end face bevel gear 3 is not marked in Figure 1A and will be described below. The bracket 1 can be fixed on the spacecraft. The main shaft 2 can be driven by a motor on the spacecraft.

[0057] As Figure 1B and Figure 1C shown, the solar sail panel 4 may include multiple movable arrays 401 that can move between a deployed state and a folded state. The number of movable arrays 401 is two or more, preferably six or more, and more preferably eight. It should be noted that the number of movable arrays 401 is an even number. In the illustrated embodiment, the number of movable arrays 401 is shown as eight.

[0058] In some alternative embodiments, the surface of the movable array 401 facing the bracket 1 may be provided with reinforcing ribs 403 to reduce the amount of deformation during the movement of the solar sail panel 4.

[0059] In some embodiments of the present invention, the solar sail panel 4 may further include a fixed array 402, but this is not necessary. The fixed array 402 can compensate for emergency electric energy on the spacecraft and supply electric energy to the excitation clutch when the movable array 401 is in the folded state. The fixed array 402 can be fixed to the bracket 1. When the movable array 401 is in the deployed state, the fixed array 402 and the movable array 401 are in the same plane. In the illustrated embodiment of the present invention, the fixed array 402 is included in the solar sail panel 4. As Figure 1B and Figure 1C shown, when the solar sail panel 4 is in the deployed state, the solar sail panel 4 generally has a regular octagon structure. Among them, the movable array 401 is composed of eight independent isosceles trapezoid structures and is circumferentially arranged in a way that the waists are opposite and the upper bases are inward and the lower bases are outward. The fixed array 402 also has a regular octagon structure, and each side corresponds to the upper base of the movable array 401 one by one with a movement gap in the middle.

[0060] The folding and unfolding mechanism of the present invention may further include a plurality of drive units respectively corresponding to multiple movable array surfaces 401, and a plurality of actuating units respectively corresponding to multiple movable array surfaces 401.

[0061] Next, with reference to Figure 2 and Figure 3 each drive unit and each actuating unit corresponding to a single movable array surface in the centralized drive type spacecraft solar sail multi-degree-of-freedom space folding and unfolding mechanism provided by the present invention will be described in detail. Figure 2 FIG. is a schematic three-dimensional view showing the movement principle of a single movable array surface in the centralized drive type spacecraft solar sail multi-degree-of-freedom space folding and unfolding mechanism according to an exemplary embodiment of the present invention. Figure 3 FIG. is a schematic three-dimensional view showing the working principle of a lead screw shaft and a transmission member in the centralized drive type spacecraft solar sail multi-degree-of-freedom space folding and unfolding mechanism according to an exemplary embodiment of the present invention.

[0062] See Figure 2 , the end face bevel gear 3 included in the folding and unfolding mechanism of the present invention can be supported by the bracket 1 and rotate together with the main shaft 2.

[0063] As Figure 2 shown, the drive unit may include a bevel gear 501, a lead screw shaft 502, and a lead screw shaft support 503. The lead screw shaft 502 has a first end 5021 and a second end 5022. In some embodiments, the lead screw shaft 502 may be designed as a hollow structure. The bevel gear 501 may be sleeved on the first end 5021 of the lead screw shaft 502 and meshed with the end face bevel gear 501. The lead screw shaft support 503 may be disposed on the bracket 1 and support the lead screw shaft 502. In the shown embodiment, the lead screw shaft support 503 is installed on the bracket 1 by means of screw connection, but the present invention is not limited thereto, and bolt connection, welding connection, or other connection methods may be specifically selected according to actual design requirements.

[0064] In some embodiments of the present invention, the lead screw shaft 502 may be arranged such that the axis of the lead screw shaft 502 is orthogonal to the axis of the main shaft 2. It should be understood that the axes mentioned herein refer to the axial axes of the respective shafts.

[0065] As Figure 3 shown, the lead screw shaft 502 may include two straight grooves 5023 located at both ends of the lead screw shaft 502 and a helical groove 5024 located between the straight grooves 5023. The straight grooves 5023 communicate with the helical groove 5024. Therefore, the lead screw shaft 502 included in the folding and unfolding mechanism of the present invention can be regarded as a specially designed lead screw. Adjusting the lead angle of the screw thread on the lead screw and the rotational speed of the drive motor can both change the movement speed of the movable array surface 401 during the folding and unfolding process.

[0066] Combined with reference Figure 2 and Figure 3 The actuating unit may include a transmission member 601 , an excitation clutch 602 , a universal joint 603 , a sailboard shaft 604 , a connecting rod 605 , a shaft support 606 , and two pressing spring switches 607 .

[0067] In the illustrated embodiment of the present invention, the transmission member 601 is generally cylindrical in shape, the transmission member 601 is sleeved on the screw shaft 502 and has a positioning column 6011 that moves in the straight groove 5023 and the spiral groove 5024 of the screw shaft 502, the positioning column 6011 protrudes radially inward from the inner circumferential surface of the transmission member 601 and is shown to be cylindrical in shape, but this is not intended to limit the present invention. The straight groove 5023 is in the circumferential direction of the screw shaft 502, the straight groove 5023 and the spiral groove 5024 are smoothly transitioned and connected without dead angles, the positioning column 6011 and the straight groove 5023 and the spiral groove 5024 are clearance-matched, the positioning column 6011 can move freely in the straight groove 5023 and the spiral groove 5024, while ensuring the relative motion margin between the two, it also ensures the smooth transmission of motion.

[0068] The second end 5022 of the screw shaft 502 can be connected to the input end of the excitation clutch 602, and the output end of the excitation clutch 602 can be connected to the sailboard shaft 604 via the universal joint 603. The rotation of the screw shaft 502 is transmitted to the sailboard shaft 604 through the universal joint 603, and the universal joint 603 realizes the multi-degree-of-freedom superposition motion of the mechanism.

[0069] like Figure 3 As shown, two pressing spring switches 607 can be respectively arranged at the transition part between the two straight grooves 5023 and the spiral groove 5024 of the lead screw shaft 502, and the two pressing spring switches 607 can be triggered under the compression of the positioning column 6011 of the transmission member 601 to independently control the closing and opening of the excitation clutch 602. In some embodiments, both the pressing spring switch 607 and the excitation clutch 602 can realize the current transmission between the wires by holding the brushes. It should be pointed out that the two shafts at the input end and the output end of the excitation clutch 602 are nested, which only isolates the rotation relationship between the two shafts in the disconnected state, while the connection relationship is still maintained.

[0070] Return to reference Figure 2 One end of the connecting rod 605 can be fixed to the transmission member 601 so that the transmission member 601 drives the connecting rod 605 to move when it moves along the screw shaft 502. The other end of the connecting rod 605 can be hinged to the rotating shaft support 606, so that the rotating shaft support 606 can be moved by the connecting rod 605 and can perform a fan-shaped sweeping motion around the axis of the main shaft 2 relative to the connecting rod 605, similar to the opening and closing motion of an umbrella.

[0071] The rotary shaft support 606 can be sleeved on the solar panel rotary shaft 604 so that the rotary shaft support 606 can rotate relative to the solar panel rotary shaft 604. Additionally, the rotary shaft support 606 can be mounted on the solar panel rotary shaft 604 such that the rotary shaft support 606 is axially fixed relative to the solar panel rotary shaft 604. It should be understood that the present invention does not limit the connection manner between the rotary shaft support 606 and the solar panel rotary shaft 604. For example, a bearing can be provided between the rotary shaft support 606 and the solar panel rotary shaft 604, or the inner ring of the bearing can be designed integrally with the solar panel rotary shaft 604 and the rotary shaft support 606 can be designed integrally with the outer ring of the bearing, as long as the above object can be achieved. The movable array surface 401 can be fixed to the solar panel rotary shaft 604 to move together with the solar panel rotary shaft 604, thereby realizing the switching of the movable array surface 401 between the deployed state and the folded state. Among them, Figure 4A FIG. shows a plan view of the solar panel 4 in the deployed state in the folding and unfolding mechanism according to an exemplary embodiment of the present invention, Figure 4B FIG. shows a plan view of the solar panel 4 in the folded state in the folding and unfolding mechanism according to an exemplary embodiment of the present invention.

[0072] In the centralized drive type spacecraft solar sail multi-degree-of-freedom space folding and unfolding mechanism according to the present invention, the hard motion contact between the positioning post 6011 and the pressing spring switch 607 realizes the cyclic reversible opening and closing of the excitation clutch 602. The positioning post 6011 moves between the straight groove 5023 and the spiral groove 5024 through the pressing spring switch 607, realizing the switching of the solar panel 4 between the folding and unfolding mode and the attitude adjustment mode. In the folding and unfolding mode, the movement of the positioning post 6011 in the spiral groove 5024 (at this time, the excitation clutch 602 is disconnected and does not transmit torque to the solar panel rotary shaft 604, and the solar panel rotary shaft 604 only makes a sectorial sweeping motion) is transmitted to the solar panel rotary shaft 604 through the connecting rod 605, and the switching of the solar panel 4 between the folded position and the deployed position can be realized. In the attitude adjustment mode, the movement of the positioning post 6011 in the straight groove 5023 (at this time, the excitation clutch 602 is closed and only transmits torque to the solar panel rotary shaft 604, and the solar panel 4 only rotates around the solar panel rotary shaft 604 without sectorial sweeping motion) can realize the attitude adjustment of the solar panel 4 between the folded position and the erected position in the folded state and between the erected position and the deployed position in the deployed state, thereby completing the switching of the movable array surface 401 between the deployed state and the folded state. The attitude adjustment of the movable array surface 401 in the attitude adjustment mode can refer to Figure 5 FIG., which is a schematic perspective view of the symmetric two pairs of movable array surfaces in the centralized drive type spacecraft solar sail multi-degree-of-freedom space folding and unfolding mechanism according to an exemplary embodiment of the present invention when adjusting the attitude in the deployed position.

[0073] It should be noted that in the attitude adjustment mode, that is, when the positioning post 6011 moves in the straight groove 5023, due to the relative position relationship of the connecting rod 605, the sailboard rotating shaft 604 and the rotating shaft support 606, the rotation central angle of the lead screw shaft 502 can be between 90° and 135°.

[0074] In the folding and unfolding mechanism of the present invention, the plurality of lead screw shafts 502 of the plurality of drive units can be arranged symmetrically about the axis center of the main shaft 2, which can be referred to Figure 6 , which shows the arrangement structure of the face bevel gear and the plurality of lead screw shafts in the folding and unfolding mechanism according to an exemplary embodiment of the present invention. Each two coaxially and oppositely installed lead screw shafts 502 perform coaxial reverse rotation movements.

[0075] Now referring back to Figure 1A , in some embodiments of the present invention, each lead screw shaft 502 is generally arranged between two movable array surfaces 401. Specifically, each lead screw shaft 502 is connected to the waist of the trapezoid of the corresponding movable array surface 401 and is parallel to the waist.

[0076] Returning to refer to Figure 3 , the actuating unit may further include two leaf springs 609, and the two leaf springs 609 can be respectively arranged at the joint positions between the two straight grooves 5023 and the spiral groove 5024 of the lead screw shaft 502, so that the positioning post 6011 moves unidirectionally in the straight groove 5023, thereby ensuring the unidirectional irreversible movement of the positioning post 6011 in the straight groove 5023.

[0077] In the exemplary embodiment of the present invention, as Figure 2 shown, the actuating unit may further include a spring piece 608, and the rotating shaft support 606 can be hinged to the connecting rod 605 via the spring piece 608.

[0078] By adopting the spring piece structure, the rigid connection between structures is greatly avoided, and the problem of motion jamming when the mechanism is in the critical dead point state is also avoided, improving the functional reliability of the folding and unfolding mechanism movement.

[0079] In the exemplary embodiment of the present invention, the actuating unit may further include a connecting element 610 located between the connecting rod 605 and the spring piece 608.

[0080] Now referring to Figure 7 to describe in detail the spring piece and the connecting element in the centralized drive type spacecraft solar sail multi-degree-of-freedom space folding and unfolding mechanism provided by the present invention. Figure 7 is a schematic perspective view of the rotating shaft support, the spring piece, the connecting element and the connecting rod in the centralized drive type spacecraft solar sail multi-degree-of-freedom space folding and unfolding mechanism according to an exemplary embodiment of the present invention.

[0081] As Figure 7As shown, one end of the connecting element 610 can be fixed to the spring piece 608. The connection manner between the connecting element 610 and the spring piece 608 is not limited and can be determined according to actual design requirements, specifically using bolt / nail connection, welding or other forms of mechanical connection. The other end of the connecting element 610 can have a cylindrical portion 6101.

[0082] In the illustrated embodiment, the connecting rod 605 is in a U shape and includes a cross bar 6051 and two legs 6052 that can be disassembled and assembled. The two legs 6052 are connected to the transmission member 601 on both sides of the transmission member 601, which can be observed from Figure 2 As shown, the connecting rod 605 is designed with hollowing for weight reduction on the premise of meeting the requirements of structural strength, stiffness and stability.

[0083] The cylindrical portion 6101 of the connecting element 610 can be sleeved on the cross bar 6051 and can rotate relative to the cross bar 6051, so that the connecting element 610 can perform a fan-shaped sweep around the axis of the main shaft 2 relative to the connecting rod 605.

[0084] In some embodiments, the actuating unit may further include two sleeves 611. The two sleeves 611 can be respectively sleeved on the cross bar 6051 on both sides of the cylindrical portion 6101, as Figure 7 shown.

[0085] Next, refer to Figure 8 to describe in detail the bracket in the centralized drive type spacecraft solar sail multi-degree-of-freedom space folding and unfolding mechanism provided by the present invention. Figure 8 is a schematic perspective view of the bracket in the centralized drive type spacecraft solar sail multi-degree-of-freedom space folding and unfolding mechanism according to an exemplary embodiment of the present invention.

[0086] As Figure 8 shown, the bracket 1 can be in a cage-like structure and is made of a light-weight and high-rigidity material. This structure plays an important role in connecting the spacecraft and the solar sail panel 4. The axis of the main shaft 2 is consistent with the axis of the bracket 1, and one axial end of the bracket 1 is connected to the spacecraft. In the illustrated embodiment, the bracket 1 is connected to the spacecraft by screws passing through the holes 101 of the bracket 1, but this is not restrictive and can be specifically selected to use bolt connection, welding connection or other connection methods according to actual design requirements. The other axial end of the bracket 1 is connected to the face cone gear 501.

[0087] The bracket 1 can include a plurality of protrusions 102 axially protruding from the other axial end of the bracket 1. The number of protrusions corresponds to the number of movable arrays 401. The space between every two protrusions 102 is used to receive the lead screw shaft support 503, which can be seen in Figure 2 this.

[0088] In addition, the electrical system wiring design can be carried out on the bracket 1 according to the actual installation requirements, or the bracket 1 can be used as the mounting bracket for the driving motor. In addition, the bracket 1 can be fixedly connected in an overlapping manner with other bracket structures or the span and size can be changed to meet the actual use requirements.

[0089] Now mainly refer to Figure 2 to describe the working process of the centralized drive type spacecraft solar sail multi-degree-of-freedom space folding and unfolding mechanism provided by the present invention.

[0090] First, when the movable front surface 401 of the solar sail panel 4 needs to be switched from the folded state as shown in Figure 4B (where the positioning post 6011 of the transmission member 601 is located in the straight groove 5023 at the first end 5021 of the lead screw shaft 502) to the unfolded state as shown in Figure 4A , the motor is powered on to drive the main shaft 2 to rotate, for example, in the clockwise direction, that is, Figure 2 the direction indicated by the dashed arrow in. The face bevel gear 3 rotates together with the main shaft 2, and a pair of coaxial and opposite bevel gears 501 meshing with the face bevel gear 3 and the lead screw shaft 502 perform relative reverse rotational movements. The positioning post 6011 first moves in the straight groove 5023 at the first end 5021 of the lead screw shaft 502, so that the sailboard rotating shaft 604 rotates and the movable front surface 401 adjusts its attitude from the folded position in the folded state to the erected position.

[0091] Then, the transmission member 601 moves along the Figure 2 direction of the dashed arrow pointing to the right in, and the positioning post 6011 moves to squeeze the pressing spring switch 607 at the first end 5021, so that the excitation clutch 602 is disengaged. The positioning post 6011 enters the spiral groove 5024 for movement. The translational movement of the transmission member 601 is transmitted to the sailboard rotating shaft 604 through the connecting rod 605, so that the sailboard rotating shaft 604 performs a sector sweeping movement, and further the movable front surface 401 moves from the erected position to the unfolded state, that is, the erected position in the unfolded state.

[0092] Then, the positioning post 6011 starts to leave the spiral groove 5024 and enters the straight groove 5023 at the second end 5022 of the lead screw shaft 502. When the positioning post 6011 squeezes the pressing spring switch 607 at the second end 5022, the excitation clutch 602 is closed, and the sailboard rotating shaft 604 only rotates without a sector sweeping movement, so that the movable front surface 401 adjusts its attitude through the attitude adjustment process to the unfolded state as shown in Figure 4A .

[0093] For the process of switching the movable front surface 401 from the unfolded state to the folded state, only the driving motor needs to be reversed, and the other processes are exactly opposite to the above unfolding process, which will not be elaborated here.

[0094] As described above, the centralized drive type spacecraft solar sail multi-degree-of-freedom space folding and unfolding mechanism provided by the present invention has the advantage of high central symmetry. Its driving main shaft is the central inertia main shaft of the mechanism, avoiding the appearance of additional dynamic loads during the movement of the mechanism, thereby affecting the stability of the spacecraft itself, and greatly reducing the dynamic load during the in-orbit service of the spacecraft. In addition, the folding and unfolding mechanism of the present invention adopts a centralized drive-distributed parallel transmission, with a single and centralized drive source and no redundancy, further expanding the space for carrying the effective payload of the spacecraft. Moreover, the folding and unfolding mechanism of the present invention can achieve multi-degree-of-freedom movement, effectively ensuring the switching between the attitude adjustment mode and the folding and unfolding mode of the sailboard. The movable array surface of the solar sail in the attitude adjustment mode can rotate around the sailboard rotating shaft to adjust the attitude, avoiding mutual interference caused by disturbances during the movement of the solar sailboard, and also improving the space storage ratio of the spacecraft. Not only that, the movable array surfaces of each sailboard of the folding and unfolding mechanism of the present invention are independently and non-crosslinked in movement, and the overall mechanism adopts a gear-ball screw transmission form, resulting in high precision of the unfolding movement.

[0095] The features mentioned and / or shown in the above description of the exemplary embodiments of the present invention can be combined in the same or similar manner into one or more other embodiments, combined with the features in other embodiments or replace the corresponding features in other embodiments. The technical solutions obtained by such combination or replacement should also be regarded as being included within the protection scope of the present invention.

Claims

1. A multi-degree-of-freedom space folding and unfolding mechanism for a solar sail of a spacecraft with centralized drive, characterized in that It includes a bracket, a main shaft, and an end face bevel gear, and also includes a solar sailboard having multiple movable arrays, multiple drive units provided in one-to-one correspondence with the multiple movable arrays, and multiple actuating units provided in one-to-one correspondence with the multiple movable arrays; The bracket is fixed on the spacecraft; The main shaft is driven by a motor on the spacecraft; The end face bevel gear is supported by the bracket and rotates together with the main shaft; The drive unit includes a bevel gear, a lead screw shaft, and a lead screw shaft support; The bevel gear is sleeved on the first end of the lead screw shaft and meshes with the end face bevel gear, and the lead screw shaft support is arranged on the bracket and supports the lead screw shaft; The lead screw shaft includes two straight grooves at both ends of the lead screw shaft and a spiral groove between the straight grooves, and the straight grooves communicate with the spiral groove; The actuating unit includes a transmission member, an excitation clutch, a universal joint, a sailboard rotating shaft, a connecting rod, a rotating shaft support, and two pressing spring switches; The transmission member is sleeved on the lead screw shaft and has a positioning post that moves in the straight grooves and the spiral groove of the lead screw shaft. The second end of the lead screw shaft is connected to the input end of the excitation clutch, and the output end of the excitation clutch is connected to the sailboard rotating shaft via the universal joint; The two pressing spring switches are respectively arranged at the transition parts between the two straight grooves and the spiral groove of the lead screw shaft, and the two pressing spring switches are triggered under the extrusion of the positioning post of the transmission member to independently control the closing and opening of the excitation clutch; One end of the connecting rod is fixed to the transmission member, and the other end is hinged to the rotating shaft support so that the rotating shaft support can perform a sector sweeping motion around the axis of the main shaft; The rotating shaft support is sleeved on the sailboard rotating shaft so that the rotating shaft support can rotate relative to the sailboard rotating shaft, and the movable array is fixed to the sailboard rotating shaft to move together with the sailboard rotating shaft, thereby realizing the switching between the deployed state and the folded state of the movable array; The multiple lead screw shafts of the multiple drive units are arranged symmetrically about the axis of the main shaft.

2. The centralized drive type spacecraft solar sail multi-degree-of-freedom space folding and unfolding mechanism according to claim 1, characterized in that: The actuating unit further includes a spring piece, and the rotating shaft support is hinged to the connecting rod via the spring piece.

3. The centralized drive type spacecraft solar sail multi-degree-of-freedom space folding and unfolding mechanism according to claim 1 or 2, characterized in that: The actuating unit further includes two leaf springs, and the two leaf springs are respectively arranged at the joint positions between the two straight grooves and the spiral groove of the lead screw shaft to enable the positioning post to move unidirectionally in the straight groove.

4. The centralized drive type spacecraft solar sail multi-degree-of-freedom space folding and unfolding mechanism according to claim 1 or 2, characterized in that: The axis of the lead screw shaft is orthogonal to the axis of the main shaft.

5. The centralized drive type multi-degree-of-freedom space folding and unfolding mechanism of a spacecraft solar sail according to claim 2, characterized in that: The actuating unit further includes a connecting element between the connecting rod and the spring piece. One end of the connecting element is fixed to the spring piece, and the other end has a cylindrical portion; The connecting rod is in a U-shaped shape and includes a cross bar and two legs that can be disassembled and assembled. The two legs are connected to the transmission member on both sides of the transmission member; The cylindrical portion of the connecting element is sleeved on the cross bar and can rotate relative to the cross bar.

6. The centralized drive type spacecraft solar sail multi-degree-of-freedom space folding and unfolding mechanism according to claim 5, characterized in that: The actuating unit further includes two sleeves, and the two sleeves are respectively sleeved on the cross bar on both sides of the cylindrical portion.

7. The multi-degree-of-freedom space folding and unfolding mechanism of the concentrated drive spacecraft solar sail according to claim 1 or 2, characterized in that: The solar panel further includes a fixed array surface, and the fixed array surface is fixed to the bracket. When the movable array surface is in the deployed state, the fixed array surface and the movable array surface are in the same plane.

8. The centralized drive type spacecraft solar sail multi-degree-of-freedom space folding and unfolding mechanism according to claim 1 or 2, characterized in that: The bracket has a cage-like structure, the axis of the main shaft is consistent with the axis of the bracket, and one axial end of the bracket is connected to the spacecraft, and the other axial end is connected to the face bevel gear.

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