Pocketed spring assembly for use in a bedding or seating product and a method of making such a pocketed spring assembly
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Solution Overview
Problem
Existing pocketed spring assemblies face challenges with semi-impermeable fabrics that are difficult to ultrasonically weld consistently and create noise due to airflow restrictions and expansion issues.
Innovation Solution
A three-layered fabric is developed, comprising a polypropylene non-woven fabric layer, an airtight thermoplastic polyurethane film layer, and a sound attenuating lofted needle punch polyester fiber batting layer, which is impermeable to airflow but allows air to enter and exit through segmented seams, enabling consistent ultrasonic welding and reducing noise.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Object-affected harmful factors
If semi-impermeable fabric is used to control airflow through the pocketed spring assembly, then airflow restriction is improved, but the fabric creates noise during spring expansion and contraction
Solution Approach 1:
The fabric is divided into multiple layers with distinct functions: an outer shell layer for structural integrity, an intermediate acoustic damping layer to absorb noise, and an inner airflow control layer with selective permeability. This segmentation allows each layer to address specific requirements without compromising the others.
Solution Approach 2:
The fabric combines multiple materials with different properties: a woven or non-woven fabric base for structural support, acoustic damping materials (such as foam or fibrous layers) for noise reduction, and selectively permeable membranes for airflow control. This composite structure resolves the contradiction by integrating materials that individually address airflow restriction and noise suppression.
2Ease of operation
If coated semi-impermeable fabric is used to slow compression and expansion rates, then luxury feel is improved, but ultrasonic welding consistency deteriorates
Solution Approach 1:
The fabric structure is segmented into distinct layers where the outer shell layer uses materials and constructions optimized for ultrasonic welding (such as thermoplastic coatings or woven structures with appropriate thermal properties), while inner layers handle the airflow control and luxury feel functions. This allows the welding surface to be optimized for manufacturing consistency while maintaining the desired operational characteristics.
Solution Approach 2:
The fabric parameters are optimized for welding by controlling the thickness, material composition, and surface properties of the outer layer to ensure consistent ultrasonic welding. The coating weight, fiber density, and thermal conductivity are adjusted within specific ranges to achieve reliable welds while preserving the luxury feel through proper layer configuration.
3Quantity of substance
If permeable fabric is used to allow free airflow through the fabric, then breathability is improved, but the fabric cannot provide airflow control for luxury feel
Solution Approach 1:
The fabric is constructed with multiple layers having different permeability characteristics. The outer shell layer may be more permeable to allow breathability, while inner layers incorporate airflow control mechanisms such as selective permeable membranes, adjustable vents, or flow-regulating structures that provide the luxury feel by controlling the rate and pattern of airflow.
Solution Approach 2:
The fabric combines materials with contrasting permeability properties: more open and breathable materials in the outer layers for airflow, and controlled permeability materials in inner layers for luxury feel. The composite structure allows simultaneous achievement of breathability and airflow control through the interaction of different material layers.
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 a pocketed spring assembly with consistent airflow control, improved durability, and reduced noise, allowing for customizable firmness zones and enhanced user comfort by regulating airflow through strategically placed gaps in the seams.
Implementation Method 1
a non-woven polypropylene fabric which is extremely permeable to airflow... fabrics which are thermally or ultrasonically weldable to themselves... transverse and longitudinal welds, instead of stitching, are used to form the pockets
Implementation Method 2
an airtight thermoplastic polyurethane film layer, which is impermeable to airflow
Implementation Method 3
allowing air to enter and exit through segmented seams
Data Source
Figure 1
Figure 1A
Figure 1B
AI summary
A pocketed spring assembly (12, 12a, 12', 12d, 12e, 12f, 12g) comprises a plurality of parallel strings (26, 26a) of individually pocketed springs (28). Each string (26, 26a) is joined to at least one adjacent string (26, 26a). Each string (26, 26a) has first and second opposed plies (48, 50) of fabric and a plurality of pockets (38) formed along a length of the string (26, 26a) by transverse segmented seams (54) joining the plies (48, 50). Gaps (66, 70) between the segments (64, 68) of the seams (52, 54) allow air to pass into and out of the pockets (38) despite the fabric being impermeable to airflow through the fabric. The size of the gaps (66, 70) determines the firmness or "feel" of the pocketed spring assembly (12, 12a, 12', 12d, 12e, 12f, 12g) or portion thereof.