Pocketed spring assembly
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Solution Overview
Problem
Current pocketed spring assemblies using spun-bonded polypropylene fabric face issues with uneven surfaces and 'steps' due to different coil spring geometries, leading to reduced firmness and increased manufacturing costs, as they require additional edge support and labor-intensive foam encasement construction.
Innovation Solution
The solution involves creating pocketed spring assemblies with strings of varying pocket sizes along their length, achieved by adjusting the location of longitudinal seams in the fabric, allowing for different coil spring geometries without altering the overall height, thereby maintaining a uniform surface and eliminating the need for additional edge support.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Adaptability or versatility
If different coil spring geometries are used to create varying firmness zones, then firmness distribution is improved, but pocket stretching occurs causing uneven surfaces and steps
Solution Approach 1:
The patent applies local quality by varying the size of individual pockets along the string based on their position. Outer pockets are made smaller than inner pockets to accommodate the different geometries of edge springs versus core springs. This local differentiation in pocket dimensions allows each pocket to properly contain its corresponding spring without excessive stretching, thereby maintaining surface uniformity while enabling varying firmness zones through different spring geometries.
2Reliability
If foam encasements are constructed to receive pocketed spring assemblies, then edge support is provided, but manufacturing complexity and labor costs increase
Solution Approach 1:
The patent merges the edge support function directly into the pocketed spring assembly by constructing the outermost pockets with reinforced dimensions that provide inherent edge support. This integration eliminates the need for separate foam encasements, as the pocketed spring assembly itself becomes a self-contained unit with built-in edge support capabilities, thereby reducing manufacturing complexity and labor costs while maintaining reliable edge support.
3Ease of manufacture
If spun-bonded polypropylene fabric is used for pockets, then manufacturing cost is reduced, but fabric stretching occurs over time causing uneven surfaces
Solution Approach 1:
The patent applies preliminary action by pre-determining and optimizing the dimensions of each pocket during manufacturing based on its position along the string. Outer pockets are designed with smaller dimensions than inner pockets before the springs are inserted. This preliminary dimensional differentiation compensates for the inherent stretching characteristics of spun-bonded polypropylene fabric, ensuring that each pocket maintains its intended dimensions and preventing uneven surfaces over time, while still utilizing the cost-effective fabric material.
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 approach ensures a pocketed spring assembly with varying firmness zones without 'steps' and a smooth surface, reducing manufacturing costs by eliminating the need for separate foam encasements and enhancing durability through built-in edge supports.
Implementation Method 1
these fabrics have been advantageously used to create strings of individually pocketed coil springs wherein transverse and longitudinal welds, instead of stitching, are used to form the pockets encapsulating the springs
Implementation Method 2
these fabrics have been advantageously used to create strings of individually pocketed coil springs wherein transverse and longitudinal welds, instead of stitching, are used to form the pockets encapsulating the springs
Data Source
Figure 1
Figure 1A
Figure 1B
AI summary
A pocketed spring assembly (12) for a bedding or seating product comprises interior (26b) and exterior (26a) parallel strings of pocketed springs of approximately the same height, each of the strings being joined to at least one adjacent string and each of the strings comprising a plurality of interconnected pockets (32, 58, 60) with each of the pockets (32, 58, 60) containing at least one spring encased in fabric. At least some of the pockets (58, 60) of the interior strings (26b) have different sizes when empty due to different locations of longitudinal seams of the pockets (58, 60) of the interior strings (26b), the pockets (58, 60) of the interior strings (26b) being approximately the same height with springs therein but of different firmness due, at least in part, to different properties of the pocketed springs.