Miniaturized Drawbar Extension Spring Design
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Solution Overview
Problem
Conventional extension springs are prone to catastrophic failure due to mechanical stresses at end hooks and are susceptible to transverse deflections caused by shock or vibration, leading to disengagement or interference with other components, especially in applications requiring precise dimensions and small sizes.
Innovation Solution
The design of a miniaturizable drawbar extension spring (MDE spring) featuring a spring coil surrounded by drawbar members and end caps, which allows for precise control of free length and dampens transverse deflections, incorporating redundancy with a second spring coil to prevent total failure in case of coil failure.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Ease of manufacture
If conventional extension springs are used, then they can be manufactured with simple structure, but they are prone to catastrophic failure due to mechanical stresses at end hooks
Solution Approach 1:
The spring system is divided into multiple independent spring coils (first spring coil and second spring coil) that can function independently. If one coil fails, the other continues to provide spring functionality, preventing catastrophic system failure while maintaining manufacturing simplicity through modular design
Solution Approach 2:
The redundant second spring coil serves as a pre-prepared backup that activates only when the first spring coil fails. This beforehand cushioning ensures continuous spring function without requiring complex failure detection or replacement mechanisms
2Device complexity
If conventional extension springs are used, then they have simple design, but they are susceptible to transverse deflections caused by shock or vibration leading to disengagement or interference
Solution Approach 1:
Multiple spring coils are merged into a single integrated spring unit that shares common end hooks and mounting points. This merging provides mutual support among coils, reducing transverse deflection and preventing disengagement while maintaining a relatively simple overall design structure
Solution Approach 2:
The additional spring coil(s) provide pre-prepared structural support that activates during shock or vibration events to prevent transverse deflection, disengagement, or interference with other components
3Volume of moving object
If small-size extension springs are manufactured, then they can fit compact applications, but they cannot be manufactured to suitably precise tolerances on physical dimensions
Solution Approach 1:
The spring system is segmented into multiple coils of smaller individual dimensions, allowing each coil to be manufactured within achievable tolerances while the cumulative assembly achieves the required overall precision and compact size
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 MDE spring achieves reliable operation with precise free length control and reduced likelihood of stress failures and interference, enhancing reliability in small-sized applications by distributing stress and providing redundancy against coil failure.
Implementation Method 1
compression of the spring exerts a force that opposes the motion of the end caps
Implementation Method 2
the drawbar members damp transverse deflections of the spring coil
Data Source
AI summary
Extension springs that can be manufactured to a small size with a precise free length are described herein. An extension spring comprises a first drawbar member and a second drawbar member that extend along a same direction. The extension spring further comprises a compression spring coil that surrounds respective portions of the draw bar members. At either end of the spring coil are positioned end caps that surround the drawbar members. The end caps provide flat surfaces on which the ends of the spring coil rest in a resting position of the extension spring. The end caps are held against bent ends of arms of the drawbar members by tension of the spring coil. When the drawbar members are drawn apart from one another, the end caps compress the spring coil. Compression of the spring coil causes forces that resist the motion of the drawbar members apart from one another.