Low-impact expandable locking mechanism for inter-satellite laser communication terminal

Abstract

The invention discloses a low-impact expandable locking mechanism for an inter-satellite laser communication terminal, and belongs to the technical field of spacecraft precision mechanisms. The mechanism comprises a base unit, a rotary unfolding unit and a memory metal unlocking unit. During locking, the slotted bolt of the memory metal unlocking pipe is connected with a load, and the torsional spring is in a compressed energy storage state. During unlocking, the memory metal pipe is heated to expand to break the bolt; then the torsion spring releases energy to drive the hinge unscrewing piece to rotate outwards and unfold, buffering and positioning are achieved by impacting the silica gel pad, and the whole mechanism is completely separated from the load movement envelope; and the travel switch synchronously outputs an unlocking signal. The memory metal non-explosive unlocking and elastic driving-buffering unfolding combined collaborative design is adopted, the technical effects of extremely small impact, no envelope interference after unlocking, high reliability and reusability are achieved, and the memory metal non-explosive unlocking and elastic driving-buffering unfolding combined collaborative design is particularly suitable for a light and small inter-satellite laser communication system sensitive to impact and strict in view field requirement.

Description

Technical Field

[0001] This invention relates to the field of precision mechanisms for spacecraft, specifically to a low-impact deployable locking mechanism for inter-satellite laser communication terminals, suitable for lightweight, high-precision inter-satellite laser communication systems. Background Technology

[0002] With the rapid development of satellite laser communication technology, inter-satellite laser communication terminals are evolving towards lighter weight, smaller size, and higher precision. During satellite launch, the laser communication payload needs to be reliably secured by a locking mechanism to withstand the mechanical environment of the launch phase; after entering orbit, it needs to be unlocked and released in a timely manner to ensure normal deployment and operation of the payload. Traditional locking mechanisms often use pyrotechnics, electromagnetic drives, or motor drives to unlock, but these methods often suffer from problems such as high impact, large size and weight, and residual mechanisms interfering with payload movement after unlocking, making it difficult to meet the requirements of lightweight and small laser terminals for low impact, low envelope, and high reliability.

[0003] For example, patent document CN114321131A discloses an electric threaded locking device for spatial load displacement. This device uses a nut-compression spring; the spring's pressure engages with the locking nut, causing the bolt to slowly rise and gradually tighten the connecting and connected components. However, its structure is complex and bulky, and the mechanism remains connected to the load after unlocking, potentially limiting the optical head's range of motion and affecting the field of view design. Furthermore, this type of mechanism often generates significant impact during unlocking, which may affect the alignment accuracy and stability of the optical system.

[0004] Therefore, there is an urgent need for a locking mechanism suitable for inter-satellite laser communication systems that can achieve low-impact unlocking, complete separation after unlocking, and non-interference with load movement while ensuring reliable locking and unlocking, and has the characteristics of reusability and high reliability, so as to meet the technical requirements of modern lightweight laser communication terminals. Summary of the Invention

[0005] To address the problems of high impact, large size and weight, and easy interference with the motion envelope after unlocking in existing inter-satellite laser communication payload locking mechanisms, this invention provides a low-impact, deployable locking mechanism that automatically separates after unlocking. It is suitable for lightweight inter-satellite laser communication terminals and can achieve low-impact unlocking while ensuring reliable locking. After unlocking, it completely detaches from the load without affecting the motion field of view and rotation envelope of the optical system.

[0006] The technical solution of the present invention is as follows: A low-impact deployable locking mechanism for inter-satellite laser communication terminals is characterized by comprising a base unit, a rotation deployment unit, and a memory metal unlocking unit. The base unit includes a hinge seat, the hinge seat having a base plate portion for fixing and an ear portion extending from the base plate portion, the ear portion having a pivot mounting hole; the hinge seat has a silicone pad mounted on one side wall of the base plate portion or the ear portion, and a limit switch mounted on the other side wall opposite to the first side wall. The rotating deployment unit includes a hinged opening piece, a deployment shaft passing through the shaft mounting hole and the hinged opening piece, and an elastic energy storage element that provides deployment driving force to the hinged opening piece. The hinged opening piece is rotatably connected to the ear portion of the hinge seat through the deployment shaft. The memory metal unlocking unit includes a memory metal unlocking tube. The tube body is fixed to the end of the hinge unscrewing piece away from the unfolding axis via a connecting structure. One end of the memory metal unlocking tube is provided with a connecting end containing a mechanically weak structure for connecting to the component to be locked. In the locked state, the elastic energy storage element is compressed and stores energy, the connecting end of the memory metal unlocking tube is connected to the component to be locked, and the hinge unscrewing piece is located at the first angle position and in contact with the limit switch; Upon unlocking, the memory metal unlocking tube is actuated by heat, causing the weak mechanical structure at its connection end to break. Subsequently, the elastic energy storage element releases energy, driving the hinge opening plate to rotate around the unfolding axis to a second angular position. At this position, the hinge opening plate contacts and cushions the silicone pad, and the memory metal unlocking tube moves with the hinge opening plate until it is completely out of the motion envelope of the component to be locked. Simultaneously, the limit switch changes state due to disengagement and outputs an unlocking signal.

[0007] Furthermore, the structure of the memory metal unlocking tube that is actuated by heat includes a memory metal tube disposed inside it and a heater for heating the memory metal tube. The mechanically weak structure is a slotted bolt disposed at the connection end. The stress generated by the thermal expansion of the memory metal tube acts on the slotted bolt, causing it to break.

[0008] Furthermore, the heater is connected to dual heating circuits that are independent and redundantly configured.

[0009] Furthermore, the elastic energy storage element is a torsion spring sleeved on the unfolding shaft, with one torsion arm of the torsion spring acting on the hinge seat and the other torsion arm acting on the hinge opening plate.

[0010] Furthermore, the preload torque of the torsion spring in the locked state is configured to a value that can reliably drive the deployment and has controllable impact, preferably providing an equivalent preload of about 1.7N deployment force.

[0011] Furthermore, the rotating deployment unit also includes a bearing disposed in the mounting hole of the rotating shaft and a hinge spacer sleeved on the deployment rotating shaft. The bearing supports the deployment rotating shaft, and the hinge spacer is located between the hinge seat and the hinge opening piece to limit the assembly gap.

[0012] Furthermore, the bearing is a miniature rolling bearing with an inner diameter of 5 mm and an outer diameter of 13 mm.

[0013] Furthermore, the connection structure is detachably snapped onto the shape memory metal unlocking tube body. Furthermore, the heater operates at 28V DC voltage, and the phase change trigger temperature of the shape memory metal tube is 80℃.

[0014] Furthermore, the maximum external envelope size of the locking mechanism in the locked state is 47.6mm × 55.7mm × 35mm.

[0015] Compared with the prior art, the beneficial effects of the present invention are: The unlocking method employs a shape-memory metal tube that expands under heat to break the slotted bolts. Combined with a torsion spring-driven rotational unfolding mechanism, this achieves a non-explosive, low-impact unlocking process. After unlocking, the mechanism automatically springs open and stops with a buffer, significantly reducing disturbance to the optical system. Once unlocked, the locking mechanism rotates and tilts outwards, detaching from the optical head's motion envelope, without obstructing the field of view or restricting rotation, providing greater freedom in the design of the optical system's layout and range of motion. The shape-memory metal unlocking tube incorporates a dual-circuit heating system, allowing for normal unlocking even if one circuit fails, enhancing the reliability of aerospace missions. A limit switch monitors the hinge's opening position in real time, providing an electrical signal for unlocking status, facilitating system monitoring and control.

[0016] It is reusable, reducing the risks associated with disassembly and assembly, and minimizing the additional costs of repeated replacements during testing. It boasts high stability with dual heating circuits, allowing for successful unlocking even if one heating circuit fails, a crucial feature in highly reliable aerospace systems. Attached Figure Description

[0017] Figure 1 and Figure 2 This is a three-dimensional structural diagram of the low-impact deployable locking mechanism for inter-satellite laser communication terminals of the present invention in the locked state. Figure 3 These are three views of the low-impact deployable locking mechanism for inter-satellite laser communication terminals according to the present invention, wherein a is the front view, b is the side view, c is the rear view, and d is the top view.

[0018] Figure 4 This is a schematic diagram showing the installation and working status of the low-impact deployable locking mechanism for inter-satellite laser communication terminals of the present invention in a simulated test environment.

[0019] In the diagram: 1—Memory metal unlocking tube; 2—Elastic baffle; 3—Hinge opening plate; 4—Unfolding pivot; 5—Hinge seat; 6—Bearing; 7—Hinge spacer; 8—Torsion spring; 9—Silicone pad; 10—Limit switch. Detailed Implementation

[0020] The technical solution of the present invention will now be clearly and completely described with reference to the accompanying drawings. Obviously, the described embodiments are only some, not all, of the embodiments of the present invention. Based on the embodiments of the present invention, all other embodiments obtained by those skilled in the art without creative effort are within the scope of protection of the present invention.

[0021] In the description of this invention, it should be noted that the terms "center," "upper," "lower," "left," "right," "vertical," "horizontal," "inner," and "outer," etc., indicate the orientation or positional relationship based on the orientation or positional relationship shown in the accompanying drawings. They are used only for the convenience of describing the invention and for simplifying the description, and do not indicate or imply that the device or element referred to must have a specific orientation, or be constructed and operated in a specific orientation. Therefore, they should not be construed as limitations on the invention. Furthermore, the terms "first," "second," and "third" are used for descriptive purposes only and should not be construed as indicating or implying relative importance.

[0022] Please see Figure 1-4 As shown in the figure, this embodiment provides a low-impact deployable locking mechanism for inter-satellite laser communication terminals. The mechanism mainly consists of three functional modules: a base unit, a rotation and deployment unit, and a shape-memory metal unlocking unit. Through the coordinated operation of these modules, it achieves reliable locking of the optical head component, low-impact unlocking, and automatic separation after unlocking.

[0023] The detailed structure and assembly relationship are as follows: 1. Base unit: This is the foundation for the mechanism's installation. For example... Figure 1 and Figure 3 As shown, the hinge seat (5) has an overall "T" shaped structure. Its horizontal base plate has multiple mounting holes, which are fixed to the satellite platform or communication terminal body structure by high-strength bolts. The vertical lug portion extends forward from the upper end of the base plate, and has two coaxial high-precision rotating shaft mounting holes machined on it. On the horizontal wall surface of the lug portion of the hinge seat 5 facing the outer side of the mechanism, a silicone pad 9 is attached with high-strength adhesive. This pad is made of space-grade damping silicone rubber, and its thickness and hardness are optimized to absorb and dissipate impact energy. On the corresponding wall surface of the hinge seat 5 facing the inner side of the mechanism (i.e., the side where the hinge unscrews during initial locking), a micro-motion limit switch 10 is installed by two screws. The trigger rod axis of the limit switch 10 is substantially horizontal to the base plate plane of the hinge seat 5.

[0024] 2. Rotation and Deployment Unit: This is the core component that enables the mechanism's motion. The hinge release plate 3 is a long strip-shaped plate with a shaft hole at one end that mates with the deployment shaft 4, and an interface for installing the memory metal unlocking tube 1 and a screw hole for fixing the elastic stop plate 2 at the other end (free end). The deployment shaft 4 is a high-hardness stainless steel smooth shaft. Two bearings 6 are miniature deep groove ball bearings with an inner diameter of 5mm and an outer diameter of 13mm, respectively press-fitted into the two shaft mounting holes on the ear seat of the hinge base 5. The hinge spacer 7 is a thin-walled stainless steel sleeve used to maintain axial clearance between the hinge base 5 and the hinge release plate 3. The torsion spring 8 is a stainless steel helical torsion spring, with its spring mean diameter clearance-fitted with the deployment shaft 4.

[0025] During assembly, first, press the two bearings 6 into the hinge seat 5. Then, fit the hinge spacer 7 onto the middle of the unfolding shaft 4. Next, pass one end of the unfolding shaft 4 through one side bearing 6, and then fit the torsion spring 8 on top in sequence. Finally, align and fit the shaft hole of the hinge opening piece 3. At this point, manually rotate the hinge opening piece 3 in the locking direction (i.e., the direction pressed against the limit switch 10) by a certain angle to pre-deform the torsion spring 8, and hook its two torsion arms into the pre-set hanging holes of the hinge seat 5 and the hinge opening piece 3, respectively. In this embodiment, the preload applied to the torsion spring 8 is set to 1.7N after calculation and testing optimization. This preload is sufficient to ensure reliable unfolding, and with the subsequent buffer design, the impact at the end of unfolding can be controlled within the allowable range. Finally, push the unfolding shaft 4 completely through the shaft hole of the hinge opening piece 3 and the other side bearing 6, and use an elastic retaining ring to axially limit it at the shaft end.

[0026] 3. Shape Memory Metal Unlocking Unit: This is crucial for achieving low-impact unlocking of non-pyrotechnic components. The shape memory metal unlocking tube 1 is a cylindrical assembly with a stainless steel outer shell. Its internal core components include: a nickel-titanium-based shape memory alloy tube with a specific phase transition temperature (80°C in this embodiment), a thin-film heating element (acting as a heater) tightly wound around the outer wall of the shape memory alloy tube, a clamping plate for fixing and force transmission, a flange nut, and a lock nut. One end of the shape memory metal unlocking tube 1 is machined with a slotted bolt. The shank of this bolt has a carefully designed annular stress groove, making it a mechanically weak point.

[0027] The slotted bolt end of the shape memory metal unlocking tube 1 protrudes from the inside of the free end of the hinge unscrew 3, and is used to directly tighten and connect with the mating threaded hole on the optical head component. The tube body of the shape memory metal unlocking tube 1 is fixed to the hinge unscrew 3 by an elastic baffle 2. The elastic baffle 2 is a spring steel sheet, U-shaped, with its arc portion tightly clamping the middle section of the shape memory metal unlocking tube 1, and its two straight wings are fixed to two protrusions on the free end of the hinge unscrew 3 by screws, realizing a rigid connection between the shape memory metal unlocking tube 1 and the hinge unscrew 3, while allowing the huge internal force generated by the expansion of the shape memory metal tube during heat unlocking to act on the internal slotted bolt without affecting the external connection.

[0028] The heater's power supply line adopts a dual-circuit independent parallel design, with each circuit capable of independently completing the heating unlocking task. Both power supplies are drawn from the onboard 28V DC bus and are controlled by a dedicated unlocking command relay.

[0029] The workflow of this embodiment is as follows: S1. Launch locking phase: (e.g.) Figure 1 , 2 As shown, the mechanism is in the locked state. The slotted bolt at the front end of the memory metal unlocking tube 1 has been screwed into the corresponding interface of the optical head component, firmly pulling and fixing the optical head in the predetermined position. In this state, under the action of the locking tension, the hinge opening plate 3 is pressed against (or slightly compressed) against the trigger rod of the limit switch 10, causing the limit switch 10 to output a "mechanism locked" status signal (such as a high level). At the same time, the torsion spring 8 is compressed by the hinge opening plate 3, storing elastic potential energy. The entire mechanism has an extremely compact shape, with a maximum three-dimensional outer envelope size of 47.6mm × 55.7mm × 35mm, achieving a lightweight design.

[0030] S2. On-orbit unlocking command: After the satellite successfully enters and stabilizes in orbit, the ground control center issues an unlocking command. The command is forwarded to the drive circuit of this institution through the satellite service system, closing the relay and applying a 28V DC voltage to the heater of the memory metal unlocking tube 1 (preferably activating both circuits simultaneously).

[0031] S3. Memory Metal Actuated Unlocking: The heater heats the internal nickel-titanium memory alloy tube to its austenitic phase transformation completion temperature (80°C) within seconds. The memory alloy tube undergoes a preset axial expansion (or radial expansion, converted into axial thrust through the structure), generating an expansion force of hundreds or even thousands of Newtons. This expansion force is transmitted and concentrated at the annular stress groove of the slotted bolt, causing the slotted bolt to smoothly "break" without significant macroscopic impact. The primary constraint between the optical head assembly and the locking mechanism is then released.

[0032] S4. Elastic Energy Deployment: At the instant the main constraint is released, the previously compressed torsion spring 8 immediately releases its stored elastic potential energy. The restoring torque of the torsion spring 8 drives the hinge opening plate 3 to rotate rapidly and forcefully outward (i.e. away from the optical head) around the deployment axis 4.

[0033] S5. Buffering and Separation: After the hinge opening plate 3 rotates approximately 90°, its specially designed protruding impact block strikes the silicone pad 9, which is pre-installed on the outside of the hinge seat 5, with a certain amount of kinetic energy. The silicone pad 9, through its viscoelastic deformation, efficiently absorbs and dissipates most of the impact energy, allowing the hinge opening plate 3 and the entire moving component fixed to it to smoothly and gently stop in the final unfolded position. Crucially, in this final position, the memory metal unlocking tube 1 and the hinge opening plate 3 are completely tilted to the lower side or outer side of the optical head component, and neither part of them is within the optical path field of view or the mechanical motion envelope designed for the optical head, achieving "complete physical separation and zero envelope interference."

[0034] S6. Status Confirmation Feedback: When the hinge release plate 3 begins to rotate and unfold, it disengages from the trigger lever of the limit switch 10. The contacts of the limit switch 10 are reset by the action of the internal spring, and the electrical signal state flips (e.g., from high level to low level). This change signal is captured and transmitted by the onboard data acquisition system as clear telemetry evidence that "the mechanism has been successfully unlocked and unfolded," greatly improving the monitorability and reliability of the mission.

[0035] Experiments have shown that this invention, through its low-impact design, increases design margin, more effectively reduces structural mass, and improves measurement accuracy and device reliability. Simultaneously, the unfolding structural design achieves a larger field of view, providing greater optimization space for the optical head structure.

[0036] Obviously, the above embodiments are merely illustrative examples for clear explanation and are not intended to limit the implementation. Those skilled in the art will recognize that other variations or modifications can be made based on the above description. It is neither necessary nor possible to exhaustively list all possible implementations here. However, obvious variations or modifications derived therefrom are still within the scope of protection of this invention.

Claims

1. A low-impact, deployable locking mechanism for inter-satellite laser communication terminals, characterized in that, Includes a base unit, a rotating deployment unit, and a memory metal unlocking unit; The base unit includes a hinge seat (5), which has a base plate portion for fixing and an ear portion extending from the base plate portion, the ear portion having a pivot mounting hole; the hinge seat (5) has a silicone pad (9) mounted on one side wall of the base plate portion or the ear portion, and a limit switch (10) mounted on the other side wall opposite to the side wall. The rotating unfolding unit includes a hinged opening piece (3), an unfolding shaft (4) passing through the shaft mounting hole and the hinged opening piece (3), and an elastic energy storage element that provides unfolding driving force to the hinged opening piece (3). The hinged opening piece (3) is rotatably connected to the ear seat of the hinge seat (5) through the unfolding shaft (4). The memory metal unlocking unit includes a memory metal unlocking tube (1). The tube body of the memory metal unlocking tube (1) is fixed to one end of the hinge unscrewing piece (3) away from the unfolding shaft (4) through a connecting structure. One end of the memory metal unlocking tube (1) is provided with a connecting end containing a mechanically weak structure for connecting to the component to be locked. In the locked state, the elastic energy storage element is compressed and stores energy, the connection end of the memory metal unlocking tube (1) is connected to the component to be locked, and the hinge unscrewing piece (3) is located at the first angle position and is in contact with the limit switch (10). When unlocking, the memory metal unlocking tube (1) is actuated by heat, causing the weak mechanical structure at its connection end to break; subsequently, the elastic energy storage element releases energy, driving the hinge opening piece (3) to rotate around the unfolding axis (4) to a second angle position. At this position, the hinge opening piece (3) contacts and buffers the silicone pad (9), and the memory metal unlocking tube (1) moves with the hinge opening piece (3) to completely disengage from the motion envelope of the component to be locked; at the same time, the limit switch (10) changes state due to disengagement and outputs an unlocking signal.

2. The low-impact deployable locking mechanism for inter-satellite laser communication terminals according to claim 1, characterized in that, The structure of the memory metal unlocking tube (1) that is actuated by heat includes a memory metal tube disposed inside it and a heater for heating the memory metal tube. The mechanically weak structure is a slotted bolt disposed at the connection end. The stress generated by the thermal expansion of the memory metal tube acts on the slotted bolt, causing it to break.

3. The low-impact deployable locking mechanism for inter-satellite laser communication terminals according to claim 2, characterized in that, The heater is connected to a dual heating circuit that is independent and redundant.

4. The low-impact deployable locking mechanism according to claim 1, characterized in that, The elastic energy storage element is a torsion spring (8) sleeved on the unfolding shaft (4). One torsion arm of the torsion spring (8) acts on the hinge seat (5), and the other torsion arm acts on the hinge opening plate (3).

5. The low-impact deployable locking mechanism according to claim 4, characterized in that, The preload torque of the torsion spring (8) in the locked state is configured to a value that can reliably drive the deployment and has controllable impact, preferably providing an equivalent preload of about 1.7N deployment force.

6. The low-impact deployable locking mechanism according to claim 1, characterized in that, The rotating unfolding unit also includes a bearing (6) disposed in the mounting hole of the rotating shaft and a hinge spacer (7) sleeved on the unfolding rotating shaft (4). The bearing (6) supports the unfolding rotating shaft (4), and the hinge spacer (7) is located between the hinge seat (5) and the hinge opening piece (3) to limit the assembly gap.

7. The low-impact deployable locking mechanism according to claim 6, characterized in that, The bearing (6) is a miniature rolling bearing with an inner diameter of 5 mm and an outer diameter of 13 mm.

8. The low-impact deployable locking mechanism according to claim 1, characterized in that, The connection structure is an elastic baffle (2) that is detachably snapped onto the body of the memory metal unlocking tube (1), and the elastic baffle (2) is fixed to the hinge unscrewing piece (3) by fasteners.

9. The low-impact deployable locking mechanism according to claim 2, characterized in that, The heater operates at a DC voltage of 28V, and the phase change trigger temperature of the memory metal tube is 80℃.

10. The low-impact deployable locking mechanism according to claim 1, characterized in that, The maximum external envelope size of the locking mechanism in the locked state is 47.6mm × 55.7mm × 35mm.

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