A floating joint for on-orbit refueling

Abstract

A floating joint for on-orbit refueling, belonging to the field of spacecraft on-orbit servicing technology, includes a passive end joint, an active end joint, a shell, and a docking mechanism connection section. The passive end joint and the active end joint are used in a plug-in fit, and a triple sealing structure is provided between the passive end joint and the active end joint. The shell and the docking mechanism connection section are fixedly connected, and a concave spherical seat and a convex spherical seat are movably arranged inside the shell. The top end of the concave spherical seat is threadedly connected to the active end joint, and the convex spherical seat is embedded and rotatably installed in the concave surface of the concave spherical seat. A groove is provided on the lower surface of the convex spherical seat, and a thrust bearing is provided between the groove and the upper surface of the docking mechanism connection section. A compression spring is provided between the convex spherical seat and the shell. This utility model can effectively overcome many technical bottlenecks of existing floating joints in terms of miniaturization, lightweighting, reliability, and structural complexity.

Description

Technical Field

[0001] This utility model relates to the field of spacecraft on-orbit servicing technology, specifically to a floating joint for on-orbit refueling. Background Technology

[0002] With the development of aerospace technology, on-orbit servicing (OOS) missions, especially on-orbit docking and refueling of spacecraft, have become a key approach to extending spacecraft lifespan and improving the efficiency of space assets. Floating joints are crucial mechanisms for eliminating eccentricity and angular misalignment at the active and passive ends of the docking structure, ensuring successful docking.

[0003] Although various types of floating joints have been developed for existing on-orbit refueling and docking mechanisms, they are mostly designed for medium and large spacecraft (such as space stations, cargo spacecraft, and high-value large satellites). They generally have problems such as complex structure and large mass and volume, making it difficult to directly apply them to on-orbit refueling and docking mechanisms for small and medium-sized spacecraft that are extremely sensitive to weight and size.

[0004] Existing floating joints suitable for on-orbit refueling and docking missions of small and medium-sized spacecraft mainly suffer from the following technical bottlenecks: Floating disconnector mechanisms: These typically employ flexible supports such as axial and radial springs to compensate for the multi-degree-of-freedom angle and eccentricity of the joint. While these solutions are simple in structure and highly reliable, their pneumatic drive mechanism is a critical component. It directly utilizes a piston principle, using gas to move the insertion tube forward, with upstream solenoid valves controlling air intake and exhaust. This necessitates a gas source, piping, and control valves for the pneumatic drive mechanism, increasing the overall weight of the docking mechanism. The mechanism incorporates three complex control mechanisms: pneumatic, electrical, and hydraulic. This complexity makes it difficult to adapt to the requirements of on-orbit refueling and docking mechanisms for small and medium-sized spacecraft.

[0005] The prior art with application number 202110492395.1 proposes an on-orbit refueling docking mechanism, in which the five-degree-of-freedom tolerance adjustment self-resetting mechanism has a floating function. This mechanism uses a method of superimposing multiple frames, spring plungers, arc-shaped guide rails, and V-shaped rollers to realize the five-degree-of-freedom floating function of the joint. Due to the superposition of multiple frames, the structure is complex and the envelope size is difficult to make very small, so the envelope weight is large. During launch and ascent, the connecting arm needs to be connected to the guide rail and fixed with a fixed seat to avoid the vibration of the rocket during ascent from damaging the five-degree-of-freedom tolerance adjustment self-resetting mechanism.

[0006] The existing floating disconnectors and five-degree-of-freedom tolerance adjustment self-resetting mechanisms all suffer from large mass and envelope, complex transmission and control, resulting in reduced reliability and high manufacturing costs due to multiple single-point failures. They do not meet the commercial application requirements of miniaturized, simple, and highly reliable floating joints for on-orbit refueling and docking mechanisms of small and medium-sized spacecraft.

[0007] In summary, existing technologies lack an on-orbit refueling docking mechanism that can simultaneously meet the requirements of miniaturization, simple structure, high reliability, and reusability. It should have a multi-degree-of-freedom floating joint with a certain range of freedom.

[0008] The purpose of this invention is to provide an innovative solution to the needs of on-orbit refueling and docking mechanisms for small and medium-sized spacecraft. Utility Model Content

[0009] The purpose of this invention is to provide a floating joint for on-orbit refueling to solve the problems mentioned in the background art.

[0010] To achieve the above objectives, this utility model provides the following technical solution: A floating joint for on-orbit refueling includes a passive end joint, an active end joint, a housing, and a docking mechanism connection section. The passive end joint and the active end joint are used in a plug-in fit, and a triple sealing structure is provided between the passive end joint and the active end joint. The housing is fixedly connected to the docking mechanism connection section, and a concave spherical seat and a convex spherical seat are movably disposed within the housing. The top end of the concave spherical seat is threadedly connected to the active end joint. The convex spherical seat is rotatably embedded in the concave surface of the concave spherical seat, and a groove is provided on the lower surface of the convex spherical seat. A thrust bearing is provided between the groove and the upper surface of the docking mechanism connection section, and a compression spring is provided between the convex spherical seat and the housing.

[0011] Preferably, the passive end connector includes a mounting surface that connects to the external spacecraft being fueled, an internal guide cone surface and an inner cylindrical surface that connect to the auxiliary active end connector, the internal guide cone surface and the inner cylindrical surface together form a connecting cavity, and a material discharge port is provided through the connecting cavity.

[0012] Preferably, the active end connector is provided with an injection channel, and the top of the active end connector is provided with a cylindrical head that is adapted to the inner cylindrical surface of the passive end connector. The lower end of the cylindrical head is provided with an external guide cone that is adapted to the built-in guide cone surface of the passive end connector. The active end connector is integrally formed with an injection pipeline interface that is connected to the injection channel.

[0013] Preferably, the inner top wall of the connecting cavity is provided with a sealing ring B groove, and the outer surface of the cylindrical head is provided with two sealing ring A grooves. The triple sealing structure includes two sealing rings A and one sealing ring B, and the sealing rings A and B are respectively installed in the sealing ring A groove and the sealing ring B groove.

[0014] Preferably, the inner cavity top wall of the housing and the concave spherical seat are both provided with annular positioning grooves, and the compression spring is fixedly installed between the two annular positioning grooves.

[0015] Preferably, a grease retention groove is formed in the concave surface of the concave spherical seat.

[0016] Compared with the prior art, the beneficial effects of this utility model are: Compact and lightweight structure: It adopts an integrated design of concave-convex spherical seat with thrust bearing and compression spring, replacing the traditional multi-spring, pneumatic piston or multi-frame structure, controlling the overall diameter within 35 mm, and the total length of the main and passive joints ≤65 mm, with a weight <100 g, meeting the stringent space and weight requirements of small and medium-sized spacecraft.

[0017] Improved reliability: The simplified structure reduces potential failure points, and the triple sealing structure (double sealing ring A + single sealing ring B) ensures leak-free fuel filling while simultaneously reducing the complexity of the docking mechanism.

[0018] Adaptive docking capability: The concave-convex spherical seat fits together to achieve angular tolerance, and the thrust bearing provides translational compensation, which can adapt to the initial docking deviation and reduce the requirements for satellite terminal positioning accuracy.

[0019] Self-resetting and cyclic use: The compression spring provides an automatic reset function after separation, supporting high-frequency "docking-separation" cycles to meet the routine on-orbit resupply needs of the satellite constellation.

[0020] Cost control: Simplified structure reduces manufacturing, testing and launch costs, improving the economics of space asset services. Attached Figure Description

[0021] Figure 1 This is a three-dimensional structural diagram of the present invention when it is not connected.

[0022] Figure 2 This is a cross-sectional structural diagram of the present invention when it is not connected.

[0023] Figure 3 This is a schematic diagram of the main structure of the present invention after docking.

[0024] Figure 4 This is a schematic diagram of the cross-sectional structure of the present invention after docking.

[0025] Figure 5 for Figure 4 Detailed image of point a in the middle.

[0026] In the diagram: 1. Passive end connector; 2. Active end connector; 3. Housing; 4. Connecting section of docking mechanism; 5. Triple sealing structure; 51. Sealing ring A; 52. Sealing ring B; 6. Compression spring; 7. Concave spherical seat; 71. Grease reservoir; 8. Convex spherical seat; 9. Thrust bearing; 10. Filling pipe interface. Detailed Implementation

[0027] The technical solutions of the present invention will be clearly and completely described below with reference to the accompanying drawings of the embodiments of the present invention.

[0028] Please see Figure 1 , Figure 2 , Figure 3 , Figure 4 and Figure 5 This utility model provides a technical solution: A floating joint for on-orbit refueling includes a passive end joint 1, an active end joint 2, a housing 3, and a docking mechanism connecting section 4. The docking mechanism connecting section 4 is used for mounting the floating joint on the external moving parts of the docking mechanism. The connecting section can be modified according to the requirements of the docking mechanism to adapt to the docking mechanism. The passive end joint 1 and the active end joint 2 are used in a plug-in fit, and a triple sealing structure 5 is provided between the passive end joint 1 and the active end joint 2. The housing 3 is fixedly connected to the docking mechanism connecting section 4, and a concave spherical seat 7 and a convex spherical seat 8 are movably arranged inside the housing 3. The top end of the concave spherical seat 7 is threadedly connected to the active end joint 2. The convex spherical seat 8 is embedded and rotatably installed in the concave surface of the concave spherical seat 7, and a groove is provided on the lower surface of the convex spherical seat 8. A thrust bearing 9 is provided between the groove and the upper surface of the docking mechanism connecting section 4. The thrust bearing 9 is used to provide a certain range of translational capability in any direction for the entire assembly of the active end joint 2 and the concave spherical seat 7. A compression spring 6 is provided between the convex spherical seat 8 and the housing 3.

[0029] It should be noted that, in combination Figure 2 As shown, the passive end connector 1 includes a mounting surface that connects to the external spacecraft being fueled, an internal guide cone surface and an inner cylindrical surface that connect to the auxiliary active end connector 2, the internal guide cone surface and the inner cylindrical surface together form a connection cavity, and a material discharge port is provided through the connection cavity.

[0030] The active end connector 2 is provided with a material injection channel, and the top of the active end connector 2 is provided with a cylindrical head that is adapted to the inner cylindrical surface of the passive end connector 1. The lower end of the cylindrical head is extended with an external guide cone that is adapted to the built-in guide cone surface of the passive end connector 1. The active end connector 2 is integrally formed with a filling pipeline interface 10 that is connected to the material injection channel.

[0031] Combination Figure 2 As shown, the inner top wall of the connecting cavity is provided with a sealing ring B groove, and the outer surface of the cylindrical head is provided with two sealing ring A grooves. The triple sealing structure 5 includes two sealing rings A51 and one sealing ring B52. The sealing rings A51 and B52 are respectively installed in the sealing ring A groove and the sealing ring B groove.

[0032] When the active end connector 2 is connected to the passive end connector 1, the two sealing rings A51 fit against the inner cylindrical surface to form two seals, while the sealing ring B52 fits against the upper surface of the cylindrical head of the active end connector 2 to form a third seal, thereby effectively ensuring that there is no leakage during the fuel filling process.

[0033] Combination Figure 4 As shown, annular positioning grooves are provided on the inner cavity top wall of the housing 3 and the concave spherical seat 7. The compression spring 6 is fixedly installed between the two annular positioning grooves to ensure the stability of the compression spring 6 after installation.

[0034] Combination Figure 5 As shown, in order to facilitate the retention of grease between the concave spherical seat 7 and the convex spherical seat 8, a grease retention groove 71 is provided in the concave surface of the concave spherical seat 7.

[0035] The total length of the active and passive joints is set within 65 mm and the weight must be less than 100 grams. The overall structural layout of the joints meets the requirements of a compact design, enabling efficient integration into the on-orbit refueling and docking mechanism of small and medium-sized spacecraft.

[0036] The overall design significantly simplifies the structure of the floating joint. An innovative combination of a concave-convex spherical seat with a thrust bearing 9 and a compression spring 6 replaces the complex layout of traditional designs involving multiple springs, pneumatic pistons, or multiple frames stacked with spring plungers, arc-shaped guides, and V-shaped rollers. This highly integrated design concept, combined with a compact and simplified structure, successfully controls the diameter of the entire docking mechanism to within 35 mm, the total length of the active and passive joints to within 65 mm, and the weight to less than 100 grams. This makes it one of the most lightweight and compact floating joint solutions currently available for on-orbit refueling docking structures, perfectly meeting the stringent space and weight constraints of small and medium-sized spacecraft. It significantly reduces the complexity of the floating joint and simultaneously reduces the complexity of the docking mechanism, greatly improving the reliability and safety of the docking process. Furthermore, the simplified structural design reduces potential failure points and enhances the inherent reliability of the system.

[0037] In addition, the entire docking and separation process is accomplished entirely by the forward and reverse movement of the external moving parts of the docking mechanism. The floating joint can withstand high-frequency "docking-separation" cycles, meeting the routine needs of future satellite constellations for on-orbit resupply and greatly improving the serviceability and economy of space assets.

[0038] In addition, the self-correcting characteristic of the compression spring 6 provides the mechanism with a restoring force after separation. The combination of the concave-convex spherical seat with the thrust bearing 9 and the compression spring 6 provides tolerance for eccentricity and angular deviation, which can adapt to the small deviations that exist during the initial docking and reduce the stringent requirements for the positioning accuracy of the satellite terminal.

[0039] Due to its simplified structure and fewer components, the manufacturing, testing, and launch costs of this mechanism (due to its lightweight design) are effectively controlled. This reduces the overall cost of the docking structure, making it highly attractive for commercial spaceflight and research projects with limited budgets.

[0040] In summary, this invention effectively overcomes many technical bottlenecks of existing floating joints in terms of miniaturization, lightweighting, reliability, and structural complexity, and provides a reliable, simple, economical and practical floating joint solution for on-orbit refueling and docking structures of small and medium-sized spacecraft, which is of great value to promoting the development of on-orbit servicing technology.

[0041] Operating principle: Before use, the connecting section 4 of the docking mechanism is fixedly installed on the external moving part of the docking mechanism. The two are connected by threads. The external moving part of the docking mechanism is used to drive the active end connector 2 of the floating joint to move towards the passive end connector 1. The end face of the active end connector 2 first contacts the inner guide cone surface of the passive end connector 1. The active end connector 2 continues to move forward and slides into the connecting cavity of the passive end connector 1. At this time, if the axis of the active and passive end connectors 1 has an angle of deviation in any direction, the concave spherical seat 7 fixed to the active end connector 2 rotates around the convex spherical seat 8, so that the axis of the active end connector 2 is adapted to the axis of the passive end connector 1. As the concave spherical seat 7 deflects, since one end of the compression spring 6 is limited in the housing 3 and the other end is limited in the concave spherical seat 7, the spiral axis of the compression spring 6 is forced to deflect synchronously with the axis of the active end connector 2. During installation, the deflection of the axis of the pre-compressed compression spring 6 accumulates elastic force for the reset after the active end connector 2 and the passive end connector 1 are separated.

[0042] As the external moving parts of the docking mechanism continue to move forward, the cylindrical head of the active end connector 2 is inserted into the connecting cavity of the passive end connector 1. The eccentricity between the axis of the active end connector 2 and the axis of the passive end connector 1 drives the thrust bearing 9, which is placed in the lower groove of the convex spherical seat 8, to translate in the eccentric direction, so that the axis of the active end connector 2 is adapted to the axis of the passive end connector 1. As it continues to move forward, the two sealing rings A51 installed on the outer surface of the cylindrical head of the active end connector 2 enter the connecting cavity of the passive end connector 1 and fit tightly with the inner cylindrical surface to form two sealing surfaces. As it continues to move forward, the end face of the cylindrical head of the active end connector 2 fits with the sealing ring B52 set on the upper wall of the connecting cavity of the passive end connector 1 to form a third sealing surface. At this time, the inner and outer guide cone surfaces of the active and passive end connectors 1 fit together, and the active end connector 2 and the passive end connector 1 are docked. The material discharge port of the passive end connector 1 is connected to the material channel of the active end connector 2.

[0043] After refueling, the docking mechanism unlocks and separates, the active and passive end connectors 1 separate, and the external moving parts of the docking mechanism drive the active end connector 2 to move backward. First, the end face of the active end connector 2 and the inner guide cone surface separate synchronously with the end face of the passive end connector 1 and the outer guide cone surface. Continuing to move backward, the cylindrical head of the active end connector 2 separates from the inner cylindrical surface of the passive end connector 1. At this time, due to the axial offset angle and eccentricity of the active end connector 2, which is in sync with the passive end connector 1, the active end connector 2 loses its suppressive force on the compression spring 6. The compression spring 6 automatically returns to its original shape, and the active end connector 2 follows the compression spring 6 to automatically return to its initial position.

Claims

1. A floating joint for on-orbit refueling, characterized in that: The device includes a passive end connector (1), an active end connector (2), a housing (3), and a docking mechanism connection section (4). The passive end connector (1) and the active end connector (2) are used in a plug-in fit, and a triple sealing structure (5) is provided between the passive end connector (1) and the active end connector (2). The housing (3) is fixedly connected to the docking mechanism connection section (4), and a concave spherical seat (7) and a convex spherical seat (8) are movably arranged inside the housing (3). The top end of the concave spherical seat (7) is threadedly connected to the active end connector (2). The convex spherical seat (8) is embedded and rotatably installed in the concave surface of the concave spherical seat (7), and a groove is provided on the lower surface of the convex spherical seat (8). A thrust bearing (9) is provided between the groove and the upper surface of the docking mechanism connection section (4), and a compression spring (6) is provided between the convex spherical seat (8) and the housing (3).

2. A floating joint for on-orbit refueling according to claim 1, characterized in that: The passive end connector (1) includes a mounting surface that connects to the external spacecraft being fueled, an internal guide cone surface and an inner cylindrical surface that connect to the auxiliary active end connector (2), the internal guide cone surface and the inner cylindrical surface together form a connecting cavity, and a material discharge port is provided through the connecting cavity.

3. A floating joint for on-orbit refueling according to claim 2, characterized in that: The active end connector (2) is provided with a material injection channel, and the top of the active end connector (2) is provided with a cylindrical head that is adapted to the inner cylindrical surface of the passive end connector (1). The lower end of the cylindrical head is extended with an external guide cone that is adapted to the built-in guide cone surface of the passive end connector (1). The active end connector (2) is integrally formed with a filling pipeline interface (10) that is connected to the material injection channel.

4. A floating joint for on-orbit refueling according to claim 3, characterized in that: The inner wall of the connecting cavity is provided with a sealing ring B groove, and the outer surface of the cylindrical head is provided with two sealing ring A grooves. The triple sealing structure (5) includes two sealing rings A (51) and one sealing ring B (52). The sealing rings A (51) and B (52) are respectively installed in the sealing ring A groove and the sealing ring B groove.

5. A floating joint for on-orbit refueling according to claim 1, characterized in that: The inner cavity top wall of the housing (3) and the concave spherical seat (7) are both provided with annular positioning grooves, and the compression spring (6) is fixedly installed between the two annular positioning grooves.

6. A floating joint for on-orbit refueling according to claim 1, characterized in that: The concave spherical seat (7) has a grease retention groove (71) in its concave surface.

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