Pocketed Spring Assembly With Variable Pockets for Uniform Mattress Support
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Solution Overview
Problem
Current pocketed spring assemblies with spun-bonded polypropylene fabric face issues of 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 parallel strings of springs where pockets of different sizes accommodate varying spring geometries, maintaining a uniform height and allowing for zones of different firmness without the need for additional edge support, using transverse and longitudinal seams in the fabric to form pockets of varying sizes that stretch uniformly to accommodate springs of different properties.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Ease of manufacture
If pockets of the same size are used in all strings, then manufacturing is simplified, but uneven surfaces and steps occur due to different spring geometries
Solution Approach 1:
The patent applies local quality by varying pocket dimensions based on location within the spring assembly. Outer pockets are made smaller than inner pockets to compensate for the different geometries of outer springs versus inner springs. This localized adjustment ensures that all springs, regardless of their position and geometry, result in a uniform top surface when compressed, eliminating steps and uneven surfaces while maintaining manufacturing feasibility.
2Reliability
If foam encasements are constructed to receive pocketed spring assemblies, then edge support is provided, but manufacturing costs and labor increase
Solution Approach 1:
The patent merges the edge support function directly into the pocketed spring assembly by incorporating outer strings of pockets with springs in those pockets. This integration eliminates the need for separate foam encasements to provide edge support, thereby reducing manufacturing steps, lowering labor costs, and simplifying the overall production process while maintaining reliable edge support.
3Ease of manufacture
If spun-bonded polypropylene fabric is used for pockets, then cost-effective welding is enabled, but fabric stretching causes uneven surfaces over time
Solution Approach 1:
The patent applies preliminary action by pre-adjusting pocket dimensions before inserting springs. Outer pockets are manufactured smaller than inner pockets to anticipate and compensate for the different forces and stretching characteristics of outer versus inner springs. This preliminary sizing adjustment ensures that after springs are inserted and the assembly is compressed, all pockets expand to achieve a uniform top surface, preventing unevenness over time while retaining the cost-effective welded construction.
Data Source
AI summary
A pocketed spring assembly comprises parallel strings, each string joined to at least one adjacent string. At least some of the strings have pockets of different sizes before springs are inserted therein to accommodate for the fabric stretching due to some of the springs exerting greater force on the fabric than other springs. The ability to create pockets of different sizes enables springs of different strengths to be inserted into the pockets along a string, the string having a generally uniform height after assembly.