Compact solar sail unfolding mechanism with large unfolding-folding ratio

Abstract

The invention belongs to the technical field of spacecrafts, and particularly relates to a compact solar sail unfolding mechanism with a large unfolding-folding ratio. Comprising a main body frame and a sail rolling mechanism, an unfolding driving mechanism, an auxiliary rolling mechanism and an unfolding arm rolling assembly which are arranged on the main body frame, the sail rolling mechanism is located at the top of the main body frame and used for rolling a sail film, an unfolding arm is rolled on the unfolding arm rolling assembly, and the tail end of the unfolding arm is connected with the sail film; the unfolding driving mechanism and the auxiliary winding mechanism are used for driving the unfolding arm winding assembly to rotate in the forward direction and the reverse direction correspondingly, and therefore the unfolding arms drive the sail film to be unfolded or wound synchronously. According to the solar sail propulsion system, modular design is adopted, and the solar sail propulsion system has the advantages of being efficient in unfolding, light in weight, high in stability and suitable for various sail film materials and is suitable for deep space exploration and long-term orbit tasks.

Description

Technical Field

[0001] The present invention belongs to the field of spacecraft technology, and in particular relates to a compact solar sail deployment mechanism with a large deployment ratio. Background Art

[0002] Solar sails are a type of aerospace propulsion technology that utilizes the radiation pressure of solar photons as propulsion. They require no fuel, offer sustained thrust, and have a long lifespan, making them an ideal propulsion method for deep space exploration and long-duration orbital missions. However, practical applications of solar sail technology still face numerous challenges, the core of which lies in the reliability and efficiency of deployment and retraction, which are directly related to the on-orbit performance of the solar sail and the success rate of the mission.

[0003] Existing solar sail deployment mechanisms commonly suffer from issues such as insufficient deployment reliability, low retraction efficiency, and heavy weight. For one thing, mechanical jamming or misalignment can occur during the deployment of the deployment arms and sail membrane, preventing the sail from achieving its designed deployed shape and reducing propulsion efficiency. Furthermore, the deployment mechanism utilizes a large amount of high-density materials and complex mechanical structures, increasing system weight and launch costs. Furthermore, existing technologies exhibit poor stability when the sail membrane is retracted, making them incapable of withstanding the high vibration and shock loads experienced during launch. Therefore, a solar sail deployment mechanism with a lightweight structure, high reliability, and strong adaptability is urgently needed. Summary of the Invention

[0004] In view of the above problems, the purpose of the present invention is to provide a compact solar sail deployment mechanism with a large deployment and retraction ratio to solve the problems of insufficient deployment reliability, low retraction efficiency and heavy weight of existing solar sail deployment mechanisms.

[0005] In order to achieve the above object, the present invention adopts the following technical solutions:

[0006] The present invention provides a compact solar sail deployment mechanism with a large deployment and retraction ratio, comprising a main frame and a sail-rolling mechanism, an deployment drive mechanism, an auxiliary retraction mechanism and a deployment arm retraction assembly arranged on the main frame, wherein the sail-rolling mechanism is located at the top of the main frame, the sail-rolling mechanism is used to retract the sail membrane, a deployment arm is retracted on the deployment arm retraction assembly, the end of the deployment arm is connected to the sail membrane, the deployment drive mechanism and the auxiliary retraction mechanism are used to drive the deployment arm retraction assembly to rotate forward and reverse respectively, thereby realizing that the deployment arm drives the sail membrane to be deployed or retracted synchronously.

[0007] There are two groups of deployment arm winding assemblies, and each group of deployment arm winding assemblies is wrapped with two deployment arms. When the two deployment arms are deployed, they extend in two vertical directions. The deployment direction of the deployment arms is controlled by a deployment arm limit rod set on the main frame.

[0008] The unfolding drive mechanism includes a motor, a gear transmission assembly, a drive belt reel and a drive belt, wherein the motor and the drive belt reel are both arranged in the main frame, the drive belt reel is located between the two unfolding arm reel assemblies, and the output end of the motor is connected to the drive belt reel through the gear transmission assembly; after the drive belt passes through the through hole on the drive belt reel, the two ends are respectively wound around the two unfolding arm reel assemblies; the motor drives the drive belt reel to rotate and reel in the drive belt, and the drive belt drives the two unfolding arm reel assemblies to rotate synchronously to realize the unfolding of the unfolding arm.

[0009] Two drive belt transition limit rods are provided in the main frame and are respectively located on both sides of the drive belt reel. The two drive belt transition limit rods are respectively used to guide the drive belts on both sides of the drive belt reel.

[0010] The unfolding arm winding assembly includes an upper limit plate on the unfolding arm, a support shaft, a unfolding arm winding shaft and a lower limit gear, wherein the upper and lower ends of the support shaft are fixedly connected to the main frame, the unfolding arm winding shaft is rotatably installed on the outside of the support shaft, and the upper and lower ends of the unfolding arm winding shaft are respectively fixedly connected to the upper limit plate and the lower limit gear on the unfolding arm, and the lower limit gear is transmission connected to the auxiliary winding mechanism.

[0011] A damping felt is provided on the upper surface of the upper limit plate of the deployment arm, and the damping felt contacts the main body frame to increase the deployment damping.

[0012] The auxiliary winding mechanism includes an auxiliary drive gear, an auxiliary drive motor and an auxiliary transmission gear, wherein the auxiliary drive motor is arranged at the bottom of the main frame, and the output end is connected to the auxiliary drive gear, the auxiliary transmission gear is arranged at the bottom of the main frame, and the auxiliary transmission gear is engaged with the auxiliary drive gear and the lower limit gears in the two sets of the unfolding arm winding assemblies.

[0013] The main frame is also provided with a plurality of pressing assemblies for pressing each of the deployment arms.

[0014] The clamping assembly includes a spring plate, a pressure plate, a spring plate shaft and a sleeve, wherein one end of the spring plate is connected to the main frame, and the other end of the spring plate is fixedly connected to the pressure plate. The sleeve is installed at the end of the pressure plate through the spring plate shaft and can rotate, and the sleeve presses the deployment arm.

[0015] The sail-furling mechanism includes an upper limit plate, a sail-furling shaft, an adapter flange, a bearing seat flange and a lower limit plate, wherein the bearing seat flange is connected to the main frame, the lower end of the sail-furling shaft is connected to the bearing seat flange through a bearing, the upper limit plate is connected to the upper end of the sail-furling shaft, and the lower limit plate is connected to the lower part of the sail-furling shaft through the adapter flange, and the sail membrane is rolled up between the upper limit plate and the lower limit plate.

[0016] The advantages and beneficial effects of the present invention are:

[0017] 1. The present invention uses a motor to drive a drive belt, which in turn drives the deployment arm to gradually deploy, making the deployment operation of the solar sail on orbit more efficient and precise, and significantly improving the operational performance of the system.

[0018] 2. The solar sail mechanism adopts a modular design, including a furling mechanism, deployment drive mechanism, deployment arm, and auxiliary retracting mechanism. Each module functions independently and works together. This design facilitates segmented commissioning and replacement during manufacturing, installation, and maintenance.

[0019] 3. The present invention significantly reduces the overall weight of the system by using composite deployment arms and high-strength lightweight materials to manufacture key components, making it suitable for quality-sensitive aerospace application scenarios. BRIEF DESCRIPTION OF THE DRAWINGS

[0020] Figure 1 This is a schematic structural diagram of a compact solar sail deployment mechanism with a large expansion-contraction ratio according to the present invention;

[0021] Figure 2 is a cross-sectional view of the sail-furling mechanism of the present invention;

[0022] Figure 3 This is an axonometric view of the unfolded drive device of the present invention;

[0023] Figure 4 A top cross-sectional view of the unfolded drive device of the present invention;

[0024] Figure 5 is a cross-sectional view of the deployment arm reeling assembly of the present invention;

[0025] Figure 6 It is a structural schematic diagram of the compression assembly in the present invention;

[0026] Figure 7 This is an axonometric view of the auxiliary winding mechanism of the present invention;

[0027] Figure 8 Comparison diagram of the sail membrane in the present invention in the rolled-up state before launch and the unfolded state after entering orbit: (a) is the rolled-up state before launch, and (b) is the unfolded state after entering orbit.

[0028] In the figure: 1 is the sail-furling mechanism, 2 is the unfolding drive mechanism, 3 is the unfolding arm, 4 is the auxiliary reeling mechanism, 5 is the upper limit plate, 6 is the sail-furling shaft, 7 is the adapter flange, 8 is the bearing seat flange, 9 is the lower limit plate, 10 is the upper cover plate, 11 is the main frame, 12 is the motor, 13 is the pressing assembly, 14 is the lower cover plate, 15 is the transmission gear, 16 is the driving gear, 17 is the drive belt transition limit rod, 18 is the unfolding arm limit rod, 19 is the support rod, 20 is the auxiliary transmission Gear, 21 is the drive belt winding shaft, 22 is the drive belt, 23 is the deployment arm winding assembly, 24 is the damping felt, 25 is the upper limit plate of the deployment arm, 26 is the support shaft, 27 is the deployment arm winding shaft, 28 is the lower limit gear, 29 is the spring plate, 30 is the rivet, 31 is the pressure plate, 32 is the spring plate shaft, 33 is the sleeve, 34 is the auxiliary drive gear, 35 is the auxiliary motor seat, 36 is the auxiliary drive motor, 37 is the sail membrane winding state, and 38 is the sail membrane unfolding state. DETAILED DESCRIPTION

[0029] In order to make the objectives, technical solutions and advantages of the present invention more clear, the present invention is described in detail below with reference to the accompanying drawings and specific embodiments.

[0030] See also Figures 1 to 8 As shown, the present invention provides a compact solar sail deployment mechanism with a large deployment and retraction ratio, including a main frame 11 and a sail-furling mechanism 1, an deployment drive mechanism 2, an auxiliary retraction mechanism 4 and a deployment arm retraction assembly 23 arranged on the main frame 11, wherein the sail-furling mechanism 1 is located at the top of the main frame 11, the sail-furling mechanism 1 is used to retract the sail membrane, a deployment arm 3 is retracted on the deployment arm retraction assembly 23, the end of the deployment arm 3 is connected to the sail membrane, the deployment drive mechanism 2 and the auxiliary retraction mechanism 4 are respectively used to drive the deployment arm retraction assembly 23 to rotate forward and reverse, thereby realizing that the deployment arm 3 drives the sail membrane to be deployed or retracted synchronously.

[0031] See also Figure 2 As shown, in an embodiment of the present invention, the sail-furling mechanism 1 includes an upper limit plate 5, a sail-furling shaft 6, an adapter flange 7, a bearing seat flange 8 and a lower limit plate 9, wherein the bearing seat flange 8 is connected to the main frame 11, the lower end of the sail-furling shaft 6 is connected to the bearing seat flange 8 through a bearing, the upper limit plate 5 is connected to the upper end of the sail-furling shaft 6, and the lower limit plate 9 is connected to the lower part of the sail-furling shaft 6 through the adapter flange 7, and the sail membrane is rolled up between the upper limit plate 5 and the lower limit plate 9.

[0032] See also Figure 3As shown, in this embodiment of the present invention, the main frame 11 includes a parallel upper cover plate 10 and a lower cover plate 14, which are connected by multiple support rods 19. Two deployment arm reel assemblies 23 are provided, each of which is wrapped with two deployment arms 3. When deployed, the two deployment arms 3 extend in two perpendicular directions. The deployment direction of the deployment arms 3 is controlled by deployment arm limit rods 18 provided on the main frame 11, thereby ensuring the accuracy and safety of the deployment process. Specifically, the upper and lower ends of the deployment arm limit rods 18 are connected to the upper and lower cover plates 10 and 14, respectively.

[0033] See also Figure 3 and Figure 4 As shown, in this embodiment of the present invention, the deployment drive mechanism 2 includes a motor 12, a gear transmission assembly, a drive belt reel 21, and a drive belt 22. The motor 12 and drive belt reel 21 are both disposed within the main frame 11. The drive belt reel 21 is located between the two deployment arm reel assemblies 23. The output end of the motor 12 is connected to the drive belt reel 21 via the gear transmission assembly. The drive belt 22 passes through a through hole in the drive belt reel 21 and is wound around the two deployment arm reel assemblies 23 at both ends. The motor 12 drives the drive belt reel 21 to rotate and retract the drive belt 22, which in turn drives the two deployment arm reel assemblies 23 to rotate synchronously, thereby deploying the deployment arms 3. The sail membrane and the deployment arms 3 deploy in coordination, ensuring that the sail membrane is taut and forming a stable solar sail structure.

[0034] Specifically, the gear transmission assembly is arranged on the bottom outer side of the lower cover 14; the gear transmission assembly includes a transmission gear 15 and a driving gear 16, the driving gear 16 is arranged at the output end of the motor 12, and the transmission gear 15 is arranged at the end of the drive belt winding shaft 21, and the transmission gear 15 and the driving gear 16 are engaged; the motor 12 drives the driving gear 16 to rotate, and the driving gear 16 drives the drive belt winding shaft 21 to rotate through the transmission gear 15.

[0035] Specifically, the diameter of the driving gear 16 is smaller than the diameter of the transmission gear 15 , and the driving torque is amplified by the transmission gear 15 and the driving gear 16 .

[0036] Furthermore, two drive belt transition limit rods 17 are provided in the main frame 11 and are located on both sides of the drive belt reel 21 . The two drive belt transition limit rods 17 are used to guide the drive belt 22 on both sides of the drive belt reel 21 .

[0037] See also Figure 5As shown, in an embodiment of the present invention, the unfolding arm winding assembly 23 includes an unfolding arm upper limit plate 25, a support shaft 26, an unfolding arm winding shaft 27 and a lower limit gear 28, wherein the upper and lower ends of the support shaft 26 are fixedly connected to the upper cover plate 10 and the lower cover plate 14 of the main frame 11 respectively, and the unfolding arm winding shaft 27 is rotatably installed on the outside of the support shaft 26 through a bearing, and the upper and lower ends of the unfolding arm winding shaft 27 are fixedly connected to the unfolding arm upper limit plate 25 and the lower limit gear 28 respectively, and the lower limit gear 28 is transmission connected to the auxiliary winding mechanism 4.

[0038] Furthermore, a damping felt 24 is provided on the upper surface of the upper limit plate 25 of the deployment arm. The damping felt 24 contacts the main frame 11 to increase deployment damping. In other words, the damping felt 24 contacts the upper cover 10 to provide rotational damping, preventing the deployment arm 3 from spontaneously expanding due to inertia during the driving process.

[0039] See also Figure 7 As shown, in this embodiment of the present invention, the auxiliary reeling mechanism 4 includes an auxiliary drive gear 34, an auxiliary drive motor 36, and an auxiliary transmission gear 20. The auxiliary drive motor 36 is mounted on the lower cover 14 of the main frame 11 via an auxiliary motor mount 35. The output end of the auxiliary drive motor 36 is connected to the auxiliary drive gear 34. The auxiliary transmission gear 20 is rotatably mounted on the lower cover 14 and meshes with the auxiliary drive gear 34 and the lower limit gears 28 in the two sets of deployment arm reeling assemblies 23. The auxiliary drive motor 36 rotates the auxiliary drive gear 34, which, through the auxiliary drive gear 20, drives the two lower limit gears 28, thereby rotating the deployment arm reeling shaft 27, achieving automatic reeling of the deployment arm 3. The drive belt 22 is wound around the deployment arm reeling assembly 23 along with the deployment arm 3. The drive belt 22 is connected to the drive belt reeling shaft 21 via a drive belt transition limit rod 17, ensuring coordinated deployment and reeling. In this embodiment, the drive belt 22 is made of steel. The auxiliary winding mechanism 4 needs to be removed in track applications to reduce mass and interference.

[0040] Further, see Figure 3 As shown, the main frame 11 is further provided with a plurality of pressing assemblies 13 for pressing each deployment arm 3 .

[0041] See also Figure 3 and Figure 6As shown, in the embodiment of the present invention, the clamping assembly 13 includes a spring plate 29, a pressure plate 31, a spring plate shaft 32, and a sleeve 33. One end of the spring plate 29 is fixedly connected to the support rod 19 of the main frame 11, and the other end of the spring plate 29 is fixedly connected to the pressure plate 31 via a rivet 30. The sleeve 33 is mounted on the end of the pressure plate 31 via the spring plate shaft 32 and is rotatable. The sleeve 33 compresses the deployment arm 3 to ensure its stability. The clamping assembly 13 provides a reliable elastic clamping function, ensuring the stability of the deployment arm 3 while reducing structural complexity.

[0042] See also Figure 8 As shown in (a), the sail film is in a small size in the retracted state 37; the deployment arm 3 is completely retracted in the deployment drive mechanism 2, and the four sail films are compactly retracted in the sail furling mechanism 1, providing reliable preparation for deployment after the mission begins. Figure 8 As shown in (a), the sail membrane is in a larger volume in the expanded state 38.

[0043] The present invention provides a compact solar sail deployment mechanism with a large expansion-contraction ratio, the working principle of which is as follows:

[0044] Motor 12 drives drive belt reel 21 to rotate and reel drive belt 22, which gradually deploys deployment arm 3. Furling mechanism 1 cooperates with deployment arm 3 to deploy and reel the sail membrane. The clamping assembly 13 compresses deployment arm 3, providing stable support during deployment and ensuring precise and reliable deployment. Auxiliary reeling mechanism 4 is specifically designed to reel deployment arm 3, ensuring the compactness of the deployment arm 3 and sail membrane prior to launch.

[0045] Before launch, the auxiliary reeling mechanism 4 will be removed to reduce the total weight and avoid additional interference during orbital operations. The auxiliary reeling mechanism 4 is only used during ground testing and pre-launch reeling operations.

[0046] Before launch, the sail is tightly wound around the furling shaft 6 and secured by the upper and lower limit plates 5 and 9 to prevent damage from vibration and impact during launch. The deployment arm 3 and drive belt 22 are secured to the deployment arm reel assembly 23 and held in place by the clamping assembly 13 to maintain the stability of the deployment arm 3 and prevent it from loosening or accidentally deploying when not in use.

[0047] During the on-track deployment process, the motor 12 drives the drive belt reel 21 through the transmission gear 15 and the driving gear 16. The drive belt 22 on the deployment arm reel assembly 23 is gradually released and guided by the drive belt transition limit rod 17 to transmit power to the deployment arm 3, causing it to gradually extend. During the deployment process, the clamping assembly 13 continuously applies a clamping force to the deployment arm 3 to provide necessary support to prevent the deployment arm 3 from becoming unstable due to vibration or external interference. The damping felt 24 contacts the upper cover plate 10 to provide damping for the rotation of the deployment arm 3 to avoid the deployment speed being too fast or too violent. As the deployment arm 3 is fully deployed, the sail-rolling mechanism 1 releases the sail membrane, which is deployed to the designed shape under the coordinated action of the deployment arm 3 and the drive belt 22, and remains in a tensioned state.

[0048] The present invention provides a compact solar sail deployment mechanism with a large deployment and retraction ratio. It adopts a modular design and has the characteristics of efficient deployment, lightweight, high stability and adaptability to a variety of sail membrane materials. It is suitable for solar sail deployment and retraction operations in spacecraft propulsion systems, and is particularly suitable for efficient control and reliable deployment of solar sails with a large deployment and retraction ratio in missions such as deep space exploration, Earth observation and orbit maintenance. Through the optimized motor drive, drive belt transmission and clamping component design, efficient deployment and retraction, lightweight structure and on-orbit stability are achieved.

[0049] The above description is only an embodiment of the present invention and is not intended to limit the scope of protection of the present invention. Any modification, equivalent replacement, improvement, expansion, etc. made within the spirit and principle of the present invention are included in the scope of protection of the present invention.

Claims

1. A compact solar sail deployment mechanism with a large deployment ratio, characterized in that: The invention comprises a main frame (11) and a sail-rolling mechanism (1), an unfolding drive mechanism (2), an auxiliary reeling mechanism (4) and an unfolding arm reeling assembly (23) arranged on the main frame (11), wherein the sail-rolling mechanism (1) is located at the top of the main frame (11), the sail-rolling mechanism (1) is used to roll up the sail film, a unfolding arm (3) is rolled up on the unfolding arm reeling assembly (23), and the end of the unfolding arm (3) is connected to the sail film, the unfolding drive mechanism (2) and the auxiliary reeling mechanism (4) are used to drive the unfolding arm reeling assembly (23) to rotate in the forward and reverse directions respectively, so that the unfolding arm (3) drives the sail film to unfold or reel synchronously.

2. The compact solar sail deployment mechanism with a large expansion and contraction ratio according to claim 1, characterized in that: The deployment arm reeling assembly (23) is divided into two groups, and each group of the deployment arm reeling assembly (23) is wound with two deployment arms (3). When the two deployment arms (3) are deployed, they extend in two vertical directions. The deployment direction of the deployment arm (3) is controlled by a deployment arm limiting rod (18) provided on the main frame (11).

3. The compact solar sail deployment mechanism with a large expansion and contraction ratio according to claim 2, characterized in that: The unfolding drive mechanism (2) comprises a motor (12), a gear transmission assembly, a drive belt reel (21) and a drive belt (22), wherein the motor (12) and the drive belt reel (21) are both arranged in the main frame (11), the drive belt reel (21) is located between the two unfolding arm reel assemblies (23), and the output end of the motor (12) is connected to the drive belt reel (21) through the gear transmission assembly; after the drive belt (22) passes through the through hole on the drive belt reel (21), the two ends are respectively wound around the two unfolding arm reel assemblies (23); the motor (12) drives the drive belt reel (21) to rotate and reel the drive belt (22), and the drive belt (22) drives the two unfolding arm reel assemblies (23) to rotate synchronously, thereby realizing the unfolding of the unfolding arm (3).

4. The compact solar sail deployment mechanism with a large expansion and contraction ratio according to claim 3, characterized in that: Two drive belt transition limit rods (17) are provided in the main frame (11) and are respectively located on both sides of the drive belt reel (21). The two drive belt transition limit rods (17) are respectively used to guide the drive belt (22) on both sides of the drive belt reel (21).

5. The compact solar sail deployment mechanism with a large expansion-contraction ratio according to claim 1, characterized in that: The unfolding arm reeling assembly (23) comprises an unfolding arm upper limit plate (25), a support shaft (26), an unfolding arm reeling shaft (27) and a lower limit gear (28), wherein the upper and lower ends of the support shaft (26) are fixedly connected to the main frame (11), the unfolding arm reeling shaft (27) is rotatably mounted on the outside of the support shaft (26), and the upper and lower ends of the unfolding arm reeling shaft (27) are respectively fixedly connected to the unfolding arm upper limit plate (25) and the lower limit gear (28), and the lower limit gear (28) is transmission-connected to the auxiliary reeling mechanism (4).

6. The compact solar sail deployment mechanism with a large expansion and contraction ratio according to claim 5, characterized in that: A damping felt (24) is provided on the upper surface of the upper limit plate (25) of the deployment arm, and the damping felt (24) contacts the main body frame (11) to increase deployment damping.

7. The compact solar sail deployment mechanism with a large expansion-contraction ratio according to claim 5, characterized in that: The auxiliary winding mechanism (4) comprises an auxiliary driving gear (34), an auxiliary driving motor (36) and an auxiliary transmission gear (20), wherein the auxiliary driving motor (36) is arranged at the bottom of the main frame (11), and the output end is connected to the auxiliary driving gear (34); the auxiliary transmission gear (20) is arranged at the bottom of the main frame (11), and the auxiliary transmission gear (20) is engaged with the auxiliary driving gear (34) and the lower limit gears (28) in the two sets of the unfolding arm winding assemblies (23).

8. The compact solar sail deployment mechanism with a large deployment ratio according to claim 1, characterized in that: The main frame (11) is also provided with a plurality of pressing assemblies (13) for pressing each of the deployment arms (3).

9. The compact solar sail deployment mechanism with a large expansion and contraction ratio according to claim 8, characterized in that: The pressing assembly (13) includes a spring plate (29), a pressure plate (31), a spring plate shaft (32) and a sleeve (33), wherein one end of the spring plate (29) is connected to the main frame (11), and the other end of the spring plate (29) is fixedly connected to the pressure plate (31). The sleeve (33) is installed at the end of the pressure plate (31) through the spring plate shaft (32) and is rotatable. The sleeve (33) presses the deployment arm (3).

10. The compact solar sail deployment mechanism with a large deployment ratio according to claim 1, characterized in that: The sail-furling mechanism (1) comprises an upper limit plate (5), a sail-furling shaft (6), an adapter flange (7), a bearing seat flange (8) and a lower limit plate (9), wherein the bearing seat flange (8) is connected to the main frame (11), the lower end of the sail-furling shaft (6) is connected to the bearing seat flange (8) via a bearing, the upper limit plate (5) is connected to the upper end of the sail-furling shaft (6), the lower limit plate (9) is connected to the lower part of the sail-furling shaft (6) via the adapter flange (7), and the sail membrane is rolled up between the upper limit plate (5) and the lower limit plate (9).

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