Coil-in-Coil Innerspring Structure for Progressive Mattress Support
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Solution Overview
Problem
Conventional innerspring designs for mattresses either prioritize affordability and rigidity or comfort and flexibility but often compromise on durability and adaptability, with physical properties constrained by wire gauge, coil height, and helical turns, failing to offer a balanced solution for varying loads and comfort.
Innovation Solution
The coil-in-coil spring design features an outside coil with fewer helical turns and a lower spring rate, nested within an inside coil with more turns and a higher spring rate, allowing for adjustable stiffness and comfort through a nested structure that accommodates both light and heavy loads by compressing the outside coil first and engaging the inside coil under increased pressure.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Ease of manufacture
If conventional innersprings with symmetrical coils are used, then manufacturing cost is reduced and ease of manufacture is improved, but the mattress surface becomes firm and rigid, reducing comfort
Solution Approach 1:
The patent applies nesting by placing an inner coil inside an outer coil to create a coil-in-coil structure. The inner coil has more helical turns and higher spring rate for support, while the outer coil has fewer turns and lower spring rate for comfort. This nested configuration allows both comfort and support functions within a single spring unit, resolving the contradiction between manufacturing simplicity and comfort.
Solution Approach 2:
The patent applies local quality by giving different regions of the spring different properties. The inner coil region has higher stiffness and more turns for structural support, while the outer coil region has lower stiffness and fewer turns for comfort. This spatial variation in properties allows the spring to provide both comfort and support simultaneously.
2Ease of operation
If pocketed coils with individual flexibility are used, then comfort is improved, but manufacturing cost increases and durability decreases due to sagging
Solution Approach 1:
The coil-in-coil structure integrates what would traditionally require separate pocketed coils into a single nested unit. The inner and outer coils work together as one integrated component, providing individual flexibility like pocketed coils but with the durability and manufacturing efficiency of conventional interconnected springs.
Solution Approach 2:
The patent merges the functions of multiple separate coils into a single coil-in-coil unit. The inner coil provides support while the outer coil provides comfort, combining what would traditionally require separate components into one integrated spring unit that is easier to manufacture and more durable.
3Device complexity
If single wire springs with fixed gauge and turns are used, then manufacturing simplicity is maintained, but adaptability to varying loads is limited
Solution Approach 1:
The nested coil structure allows the spring to adapt to varying loads through a progressive engagement mechanism. Under light loads, only the outer coil is active providing comfort. Under heavy loads, the inner coil engages to provide additional support. This progressive engagement provides adaptability while maintaining relatively simple manufacturing.
Solution Approach 2:
The patent applies dynamics by creating a spring system that changes its effective stiffness based on the applied load. The transition from outer coil engagement to inner coil engagement creates a dynamic response that adapts to varying weights, allowing the same spring to comfortably support both light and heavy loads.
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
This design provides a comfortable, resilient mattress surface that transitions smoothly between light and heavy loads, maintaining support and absorbency without discomfort or damage, with the outside coil compressing initially and the inside coil engaging under concentrated loads, offering a balanced solution for both sleeping and seating.
Implementation Method 1
The outside coil contains more helical turns or convolutions than the inside coil and thus also has a greater spring rate than the inside coil
Data Source
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AI summary
A mattress innerspring comprising a plurality of interconnected coil-in-coil springs, each coil-in-coil spring having an outside helical coil (10) and an inside helical coil (20) which is connected to the outside helical coil, the outside helical coil having an upper end convolution (30) and a lower end convolution opposite the upper end convolution, an uncompressed height of approximately 8.25 inches and a 4 or more helical convolutions, the inside helical coil having an upper end convolution and a lower end convolution opposite the upper end convolution, an uncompressed height of approximately 5.75 inches and 6 or more helical convolutions, wherein a diameter of the upper end convolution of the outside helical coil is approximately 64 mm and a diameter of the previous convolutions of the outside helical coil is approximately 70 mm, wherein a diameter of the lower end convolution of the inside helical coil is approximately 40.8 mm and a diameter of other convolutions of the inside helical coil is approximately 32.8 mm, and wherein a wire gauge of the coils is in an approximate range of between 14 and 15.5 and each coil is double-annealed, arranged in a matrix and laced together with helical lacing wire.