Activated Carbon Filter Edge Sealing with Hot-Melt Threads
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Solution Overview
Problem
Existing combination filters with activated carbon and non-woven material layers face issues with sealing end folds, leading to activated carbon particle leakage due to inadequate welds, especially with thick layers, and adhesive solutions compromising the filter function.
Innovation Solution
Sealing open edges with a fine web of hot-melt threads applied via a spray nozzle, which acts as a filter medium, preventing particle leakage while maintaining the filter's effectiveness.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Reliability
If thermal welding or mechanical sealing is used to seal end folds, then sealing strength is improved, but weld material becomes insufficient with thick activated carbon layers, leading to sealing failure
Solution Approach 1:
The invention extracts the sealing function from the activated carbon layer by using a separate nonwoven fabric layer specifically dedicated to sealing. This allows the activated carbon layer to maintain its full thickness for filtering functionality while the separate nonwoven layer provides sufficient material for reliable thermal or mechanical welding at the end folds, eliminating the conflict between layer thickness and weld material availability.
Solution Approach 2:
The nonwoven fabric layer acts as an intermediary element between the activated carbon layers, providing a dedicated sealing interface. This intermediary layer enables effective welding without requiring the activated carbon itself to be scraped away or reduced in thickness, thus maintaining both sealing reliability and filter functionality.
2Ease of manufacture
If activated carbon is scraped away at the cut edge to expose nonwoven layers for welding, then welding becomes possible, but activated carbon particles are lost and filter function is reduced
Solution Approach 1:
The nonwoven fabric layer is preliminarily positioned and integrated with the activated carbon layer before the cutting and welding operations. This preliminary arrangement ensures that sufficient nonwoven material is already in place at the end folds to serve as welding material, eliminating the need for subsequent scraping operations that would cause activated carbon loss.
3Reliability
If adhesive bead is applied to seal the end fold, then sealing is achieved, but adhesive buildup creates leaks and reduces filter function
Solution Approach 1:
The invention replaces the chemical bonding method (adhesive application) with a mechanical/thermal bonding method (thermal welding or mechanical interlocking of nonwoven layers). This substitution eliminates the adhesive buildup problem that causes leaks, while still achieving reliable sealing through the dedicated nonwoven fabric layer at the end folds.
4Manufacturing precision
If end folds are sealed with conventional methods, then sealing is attempted, but quality defects occur with thick activated carbon layers
Solution Approach 1:
The invention segments the filter structure into distinct functional zones: the activated carbon layers for filtering and a separate nonwoven fabric layer system for sealing. This segmentation allows each layer to be optimized for its specific function - the activated carbon can be made thick for better filtration while the nonwoven layer provides the necessary thickness for high-quality welding without compromising either function.
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 method effectively seals the end folds without impairing the filter function, ensuring cleanliness and preventing activated carbon particles from escaping, even with thick layers, while being cost-effective and minimizing leakage points.
Implementation Method 1
The fabric is spun in such a way that it acts like a filter medium. It has been found that, despite visually apparent free spaces/filter pores between the threads, the activated carbon particles are effectively prevented from trickling out.
Implementation Method 2
The threads could consist of an adhesive or a hot-melt adhesive, namely a so-called hot melt. An open edge of an end fold, especially a cut edge, can be sealed with hot melt threads
Data Source
Figure 1
AI summary
A filter element (1) comprising an activated carbon layer (2a), wherein the activated carbon layer (2a) terminates in an edge (4), is characterized, with regard to the objective of providing a filter element which, after cost-effective and trouble-free manufacturing, is sealed in the end region in such a way that no activated carbon particles trickle out of it and the filter function of the activated carbon is impaired as little as possible, in that the edge (4) has a spun fabric (5) of threads (6) which is arranged to prevent the escape of activated carbon from the edge (4).