Pocketed spring assembly
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Solution Overview
Problem
Current pocketed spring assemblies made with spun-bonded polypropylene fabric often result in uneven surfaces due to stretching, leading to undesirable 'steps' and requiring additional edge support, which increases manufacturing costs and reduces firmness differential across zones.
Innovation Solution
The use of pocketed spring assemblies with exterior and interior strings of varying pocket sizes, created by adjusting the location of longitudinal seams, allows for different coil spring geometries to be accommodated without stretching, maintaining a uniform height and eliminating the need for additional edge support.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Ease of manufacture
If spun-bonded polypropylene fabric is used to create pocketed spring assemblies, then manufacturing cost is reduced and production efficiency is improved, but the fabric stretches over time causing uneven surfaces and undesirable steps
Solution Approach 1:
The patent changes the physical-chemical parameters of the fabric by using a woven polyester fabric instead of spun-bonded polypropylene. This material substitution maintains cost-effectiveness while eliminating the stretching problem, thereby preserving surface uniformity over time.
Solution Approach 2:
The patent employs a composite construction combining woven polyester fabric with specific stitching patterns and pocket configurations. This composite approach creates a more durable structure that resists fabric stretching while maintaining the cost benefits of synthetic materials.
2Manufacturing precision
If additional edge support is added to prevent uneven surfaces, then surface uniformity is improved, but manufacturing complexity and cost increase
Solution Approach 1:
The patent extracts and eliminates the need for separate edge support components by addressing the root cause of uneven surfaces through material selection and pocket design. The solution is built into the basic construction rather than added as a separate element.
Solution Approach 2:
The pocketed spring assembly becomes self-supporting through the use of durable woven fabric and properly designed pocket structures that prevent stretching without requiring additional edge support mechanisms. The system serves its own structural needs.
3Adaptability or versatility
If different coil spring geometries are used to create firmness zones, then adaptability is improved, but fabric stretching increases causing steps and uneven surfaces
Solution Approach 1:
The patent applies different spring geometries and pocket configurations to specific zones within the mattress to create localized firmness variations. The durable woven fabric construction ensures that these local variations do not result in overall surface unevenness or steps.
4Ease of manufacture
If foam edge supports are used instead of pocketed spring edge supports, then manufacturing cost is reduced, but durability and edge support quality deteriorate
Solution Approach 1:
The patent avoids using short-lived foam edge supports and instead employs durable woven fabric pockets with coil springs that provide long-term edge support. The solution maintains cost-effectiveness while significantly improving durability.
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 solution ensures a smooth upper surface and reduces manufacturing costs by eliminating the need for additional edge support, while enabling different firmness zones without the appearance of 'steps', enhancing the durability and appearance of the spring assembly.
Implementation Method 1
folding an elongate piece of fabric in half lengthwise to form two plies of fabric and stitching transverse and longitudinal seams to join the plies of fabric to define pockets within which the springs were enveloped
Implementation Method 2
thermally or ultrasonically weldable to themselves. One such cost-effective fabric is a spun-bonded polypropylene fabric. By using such welding techniques, 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 3
thermally or ultrasonically weldable to themselves
Implementation Method 4
A pocketed spring assembly may be surrounded with a border made of foam or any other suitable material to provide edge support around the perimeter of the pocketed spring assembly. Such a pocketed spring assembly is mounted upon a base and is completely enclosed within an upholstered covering material
Data Source
Figure 1
Figure 1A
Figure 1B
AI summary
A pocketed spring assembly (12, 13, 12a, 12c) comprises parallel strings (26a, 26b, 27, 26aa, 26bb, 26c, 26c), each string joined to at least one adjacent string. At least some of the strings have pockets (32, 58, 60, 76, 90, 92, 58c, 59c, 60c) of different sizes before springs (36, 62, 78, 94) 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 (36, 62, 78, 94) of different strengths to be inserted into the pockets (32, 58, 60, 76, 90, 92, 58c, 59c, 60c) along a string (26a, 26b, 27, 26aa, 26bb, 26c, 26cc), the string having a generally uniform height after assembly.