Articulated Joint with Progressive Spring for Solar Panel Deployment
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Solution Overview
Problem
Existing joints for unfolding solar generators or reflectors in aerospace applications experience high loads due to varying unfolding torque, particularly at the start and end of the process, where frictional torques from electrical conductors can cause sudden locking and high material stress, leading to design challenges in component sizing.
Innovation Solution
A joint with a progressive drive spring characteristic curve that increases over the unfolding angle to compensate for varying frictional torque, ensuring a higher torque at the end of the process to counteract frictional forces, thereby reducing locking torque and material load throughout the unfolding process.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Strength
If a constant force spring is used to provide uniform unfolding torque, then the loads on system components are reduced, but frictional torques from electrical conductors cause sudden locking and high material stress at the end of unfolding
Solution Approach 1:
The patent applies parameter changes by transitioning from a constant force spring to a progressive force spring. The spring characteristic is deliberately designed to vary the unfolding torque as a function of the unfolding angle, increasing torque toward the end of the unfolding process to compensate for frictional torques from electrical conductors and ensure reliable locking without sudden halts.
2Reliability
If the unfolding torque is increased at the end position to overcome friction, then locking reliability is improved, but material load and interference torques on the axis increase
Solution Approach 1:
The patent applies dynamics by making the unfolding torque dynamic rather than static. The progressive force spring creates a torque profile that adapts to the unfolding angle, providing lower torque at the beginning (reducing material load) and higher torque at the end (improving locking reliability). This dynamic torque distribution optimizes both competing requirements.
3Reliability
If frictional torques from electrical conductors are compensated for, then sudden locking is prevented, but the joint complexity and drive system complexity increase
Solution Approach 1:
The patent resolves the contradiction by changing the physical parameter of the spring characteristic rather than adding complex control systems. The progressive force spring's geometry is designed to inherently compensate for frictional torques through its varying mechanical advantage, achieving smooth unfolding without electronic controls or additional actuators.
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 progressive spring characteristic curve maintains a consistent and sufficient unfolding torque, reducing material stress and allowing for higher frictional torques, ensuring reliable operation even in adverse conditions by matching the spring torque to at least triple the frictional torque, thus preventing sudden locking and optimizing component design.
Implementation Method 1
a drive spring of the drive has a progressive characteristic curve over the unfolding angle of the two half joints, which increases over the unfolding
Data Source
AI summary
A joint for unfolding and locking a solar generator or a reflector, or other aerospace components that can be unfolded, includes two half joints, a joint axis, and a drive. A drive spring of the drive has a progressive characteristic curve over the unfolding angle of the two half joints, which increases over the unfolding, to compensate for a frictional torque that varies over the unfolding angle.