Spiral Disc Spring Structure for Uniform Axial Deflection
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Solution Overview
Problem
Conventional force sensing elements, such as single helical springs, are inadequate for high-pressure applications due to non-uniform deflection, which causes side-loading and reduced lifespan, and are often too bulky or costly for aircraft use.
Innovation Solution
A force sensing spring element with a unitary body featuring multiple symmetrical spirals and nested helical flights with non-uniform wall thickness, designed to deflect uniformly and symmetrically, minimizing torsional motion and ensuring continued functionality even if one section fails.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Device complexity
If a single helical spring is used as a force sensing element, then the device is simple in structure, but the spring deflects non-uniformly under high pressure causing side-loading and reduced reliability
Solution Approach 1:
The single helical spring is segmented into multiple independent helical springs arranged in parallel. Each spring deflects uniformly independently, preventing side-loading and maintaining reliability under high pressure. The segmentation distributes the load across multiple springs, ensuring uniform deflection characteristics.
Solution Approach 2:
Multiple helical springs are nested concentrically around a central axis, with each spring having progressively larger dimensions. This nested arrangement allows all springs to deflect uniformly together while maintaining compact structure. The nesting principle enables the multi-spring system to achieve uniform deflection without significantly increasing overall device size.
2Ease of manufacture
If a single helical spring is used, then manufacturing is simple, but the spring has short life duration due to continuous high-pressure loading
Solution Approach 1:
The load is segmented across multiple springs, reducing the stress burden on each individual spring. This segmentation extends the lifespan of each spring by distributing the continuous high-pressure loading, while the collective system maintains the required force sensing capability. Each spring experiences reduced cyclic stress, extending fatigue life.
Solution Approach 2:
The multi-spring configuration provides built-in redundancy and stress distribution before failure can occur. If one spring degrades, the others continue to bear load, providing cushioning against complete system failure. This prior cushioning approach extends the operational life of the force sensing element.
3Force
If conventional force sensing elements are used, then they can handle high forces, but they are too bulky for aircraft applications
Solution Approach 1:
Multiple helical springs are nested concentrically, with inner springs having smaller dimensions and outer springs having progressively larger dimensions. This nested arrangement achieves high force handling capacity through the combined effect of multiple springs while maintaining a compact overall volume. The space utilization is optimized by placing springs in concentric layers.
Solution Approach 2:
The force sensing capability is enhanced by adding the radial dimension with multiple concentric springs, rather than simply increasing the size of a single spring in one dimension. This multi-dimensional arrangement achieves high force capacity with compact volume by utilizing radial space efficiently.
4Ease of manufacture
If conventional force sensing elements are used, then they are simple to produce, but they are too costly for aircraft applications
Solution Approach 1:
The force sensing element is segmented into multiple standardized helical springs that can be manufactured using conventional spring manufacturing processes. Each spring is a simple, well-understood component that can be produced efficiently. The segmentation allows for modular assembly and replacement, improving cost efficiency despite the multi-component structure.
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 solution provides high precision and accuracy with less than 1% non-linearity, enabling effective stress distribution and extended lifespan, while being less bulky and costly to produce, making it suitable for high-pressure applications like aircraft actuators.
Implementation Method 1
The disc spring is uniformly deflectable along the central axis in response to force acting on the disc spring
Data Source
AI summary
A force sensing element is used in a pressure transducer. The force sensing element includes a flat, disc-type spring having a unitary body that circumscribes a central axis, and a plurality of spirals that are continuous with each other and extend radially outwardly from the central axis. The plurality of spirals includes nested symmetrical flights having walls with a non-uniform thickness, and the disc spring is uniformly deflectable along the central axis in response to force acting on the disc-type spring. The spring is configured to have a high accuracy and a high fatigue life such that the spring is suitable for use in high-pressure applications that may require repeatability while operating with over 10 million cycles of unidirectional or bi-directional axial loading.