Separable Roller Screw Assembly for Low-Shock Spacecraft Release
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Solution Overview
Problem
Current spacecraft separation systems face challenges in ensuring safe and controlled separation of spacecraft elements with minimal shock and disturbance, while maintaining reliability and security during the journey into space.
Innovation Solution
A separable roller screw assembly featuring a planetary roller arrangement with rotatable rollers around two screw shafts, encapsulated by a rotatable nut module, allowing for axial displacement and load distribution, which stores kinetic energy and reduces frictional losses through rolling friction, enhancing control and reliability during separation.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Reliability
If pyrotechnic fasteners or pneumatic systems are used for separation, then separation can be initiated, but shock and disturbance levels increase and control precision decreases
Solution Approach 1:
The patent replaces pyrotechnic and pneumatic separation systems with a mechanical roller screw assembly that converts rotational motion to axial displacement. This mechanical substitution eliminates the shock and disturbance associated with explosive or high-pressure gas systems while providing precise, controlled separation through the threaded engagement of rollers with the screw shafts.
Solution Approach 2:
The roller screw assembly enables dynamic control of the separation process by allowing the first screw shaft to rotate and displace axially relative to the second screw shaft. The planetary roller arrangement can be controlled to rotate at regulated speeds, providing smooth, progressive separation rather than sudden violent separation, thereby reducing shock and disturbance.
2Reliability
If traditional threaded connections are used, then secure attachment is achieved, but separation control and reliability are insufficient
Solution Approach 1:
The connection system is segmented into multiple independent rollers (at least three) arranged in a planetary configuration around the screw shafts. This segmentation allows the separation force to be distributed across multiple contact points, improving reliability while enabling controlled separation through the coordinated rotation of individual rollers along their threaded paths.
Solution Approach 2:
The roller screw assembly serves multiple functions: it provides secure attachment during launch and orbit through threaded engagement, enables controlled separation through rotational displacement, and distributes loads axially and radially. This multi-functionality improves reliability by consolidating attachment and separation control into a single integrated mechanism.
3Strength
If axial loads are concentrated on single connection points, then attachment strength is achieved, but frictional losses increase and control efficiency decreases
Solution Approach 1:
The axial load is segmented and distributed across multiple rollers (at least three) that contact the screw shafts at different angular positions. This segmentation of load paths reduces the frictional loss at each individual roller-screw interface while maintaining overall attachment strength through the cumulative effect of multiple contact points working in parallel.
Solution Approach 2:
The planetary roller arrangement distributes loads in both axial and radial dimensions simultaneously. The rollers are positioned to handle axial tensile forces while their radial arrangement around the screw shafts provides radial load support. This multi-dimensional load distribution improves mechanical efficiency by reducing concentrated frictional losses.
Applied Scientific Principles
This section explains which scientific principles are used to turn an abstract innovation direction into a practical engineering solution.
Function Achieved in This Case
The separable roller screw assembly improves the control and reliability of spacecraft separation by minimizing shock and disturbance, ensuring secure attachment during launch and orbit, and efficiently managing axial and radial loads through its unique configuration.
Implementation Method 1
stores kinetic energy and reduces frictional losses through rolling friction
Data Source
Figure 1a~1b
Figure 2a
Figure 2b
AI summary
The present disclosure relates to a separable roller screw assembly comprising: a first screw shaft having a first external thread and being axially separated from a second screw shaft having a second external thread; a planetary roller arrangement comprising multiple rotatable rollers radially arrayed about the first and second screw shafts, whilst being encapsulated by a rotatable nut module; the rotatable nut module being coaxially arranged about the first and second screw shafts and configured for maintaining the planetary roller arrangement,the first and second screw shafts in an axially fixed configuration to permit the assembly to carry a load in an axial direction corresponding to an axial tensile force, whilst enabling displacement of the first screw shaft relative to the second screw shaft when said assembly is released from said axially fixed configuration; and wherein each one of the multiple rollers comprises first and second roller external thread regions adapted to engage said first external thread and said second external thread, respectively. Moreover, the present disclosure relates to a space craft release mechanism for separating a first space craft element from a second space craft element and comprising a separable roller screw assembly. In addition, the present disclosure relates a clamp band system for a load bearing interface assembly of a space craft comprising a separable roller screw assembly.