Tension Spring Mounts With Grooved End Caps
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Solution Overview
Problem
Existing end-mounting systems for tension springs suffer from insecure attachments, stress concentrations, and single-point failures, leading to potential system failure when one spring fails, especially in applications requiring high reliability and safety.
Innovation Solution
A dual-spring system with cylindrical end mounts and keyholes provides a secure attachment by encasing an inner spring within an outer spring, eliminating fasteners and distributing stress, while the end mounts hold the springs in alignment, reducing the mass of each spring and increasing system strength and safety through a higher natural frequency.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Reliability
If a single spring system is used, then the device complexity is reduced, but the reliability deteriorates because single-point failures cause whole system failure
Solution Approach 1:
The patent implements a nested spring configuration where an inner spring is placed inside an outer spring, both sharing common end mounts. This nesting arrangement provides redundancy (improving reliability) while minimizing the space envelope and avoiding the need for separate mounting structures (managing complexity). The inner spring has a smaller diameter than the outer spring, allowing it to fit within the outer spring's coil structure.
Solution Approach 2:
The spring system is segmented into two independent springs (inner and outer) that can fail independently. Each spring is a separate functional element with its own load-bearing capacity, so that failure of one segment (spring) does not necessarily cause complete system failure. The end mounts serve as common infrastructure for both segments.
2Volume of moving object
If nested springs are used to reduce space envelope, then the volume is reduced, but stress concentrations increase at the hook and mounting points
Solution Approach 1:
The patent introduces cylindrical end mounts as intermediary components between the spring hooks and the fixtures. These end mounts have grooves that the spring coils wind around, creating a distributed attachment interface. This intermediary structure eliminates stress concentrations at the hook-fixture interface by distributing the load around the circumference of the cylindrical end mount, while the grooves provide mechanical interlocking.
Solution Approach 2:
The spring coils themselves act as flexible elements that wrap around the cylindrical end mounts with grooves. This flexible wrapping creates a distributed stress distribution around the end mount circumference, replacing concentrated hook stresses with distributed contact stresses along the groove path. The spring's inherent flexibility allows it to conform to the end mount geometry.
3Ease of manufacture
If traditional hook attachments are used, then the ease of manufacture is improved, but the attachment security deteriorates due to insecure connections
Solution Approach 1:
The cylindrical end mounts with grooves serve as intermediary components that provide secure mechanical interlocking. The spring coils wind around these end mounts, creating a friction-based and geometric interlock that is more secure than simple hook attachments. The grooves in the end mounts engage with the spring coils, preventing detachment while maintaining ease of assembly through a simple winding action.
Solution Approach 2:
The patent uses cylindrical (curved) end mounts instead of flat or angular attachment surfaces. The cylindrical geometry with circumferential grooves provides a curved interface that the spring coils can wrap around, creating a more secure mechanical interlock. The curvature distributes stresses and provides a larger contact area compared to traditional flat hook-fixture interfaces, enhancing attachment security.
4Weight of moving object
If the spring diameter is reduced along the spring length, then the weight is reduced, but the attachment security at the ends deteriorates
Solution Approach 1:
The patent applies local quality by having the spring coils wind around cylindrical end mounts with grooves at the ends, creating localized attachment zones. The spring can be optimized with reduced mass in the mid-section while maintaining secure attachment at the ends through the winding configuration on the end mounts. The grooves in the end mounts provide localized mechanical interlocking that secures the spring ends without requiring increased spring diameter throughout the entire length.
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 dual-spring system offers a more secure, reliable, and lightweight attachment that minimizes failures, reduces stress concentrations, and enhances safety by avoiding dangerous frequency coupling and maintaining alignment even if one spring fails, thus improving the overall reliability and safety of spring-based applications.
Implementation Method 1
as the spring is tensioned the increased inward forces of the spring hold the spring on the end mount in a fashion similar to a Chinese finger trap
Data Source
AI summary
End mounts are used to secure a helical tension spring to end fixtures with various shapes and sizes. These end mounts contain an inner hole to encase the inner spring end mount and secure the end mount making it like a cap. There is also a keyhole created in the top surface that goes through the end mount allowing it to fit over the fixtures but not over the inner end mount, holding it in place. Grooves are machined in a helical pattern on the cylindrical side wall of the end mount. The spring is wound onto the grooves of the end mount.