Filter bag for pocket air filters
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Solution Overview
Problem
Conventional filter bags for pocket air filters have a reduced effective filter area due to their trapezoidal design, which is necessary to maintain even airflow but limits the available filtering space.
Innovation Solution
The filter bag design features side parts welded together on three sides with flexible material webs forming a zig-zag pattern, where the welding portion width increases towards the bottom edge, allowing for adjustable web portion widths and a more flexible filter bag structure, potentially increasing the filter area by varying the web portion widths.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Manufacturing precision
If the filter bags are designed with a continuously reducing cross-section from opening to bottom edge, then the distance between adjacent filter bags can be controlled and airflow can be made even, but the effective filter area is reduced
Solution Approach 1:
The filter bag is divided into multiple segments along its height, with each segment having a different cross-sectional area. The side parts are segmented into upper, middle, and lower portions, where the upper portion has a larger cross-section for maximum filtration area, the middle portion transitions to a smaller cross-section for proper spacing, and the lower portion maintains the reduced cross-section. This segmentation allows the filter bag to maximize filter area while still achieving the required distance control between adjacent filter bags.
2Manufacturing precision
If the web portion width is decreased from opening side to bottom edge to reduce distance between side parts, then the filter area is reduced due to trapezoidal design
Solution Approach 1:
Different portions of the filter bag are given different local qualities in terms of cross-sectional dimensions. The upper side parts have a first cross-sectional area optimized for maximum filtration, while the lower side parts have a second, smaller cross-sectional area optimized for spacing control. This local differentiation allows each portion to perform its specific function optimally without compromising the overall filter area.
3Ease of operation
If the side parts are made trapezoidal to facilitate installation and maintain cross-sectional shape, then the filter area is reduced
Solution Approach 1:
The filter bag employs a dynamic, multi-stage cross-sectional design rather than a static trapezoidal shape. The side parts transition from a larger cross-section in the upper portion to a smaller cross-section in the lower portion, creating a stepped or segmented configuration. This dynamic design maintains the installation advantages of defined geometric shapes while maximizing the overall filter area by avoiding the continuous tapering of a simple trapezoid.
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 design enhances the filter area by allowing for adjustable web portion widths, enabling a more even airflow and reducing pressure drop, thus improving the overall filtration efficiency and flexibility in filter bag design.
Implementation Method 1
The welding device has several sonotrodes, with which the filter material webs and the flexible material web can be welded together by ultrasound.
Data Source
AI summary
A filter bag for pocket air filters has two abutting side parts which are made of an air-permeable filter material that is weldable by ultrasound. The side parts are continuously welded to one another in side edge portions on three sides of the side parts so that a pocket having two opposite side edges, a bottom edge and an opening opposite said bottom edge is formed. Several webs made from a flexible material web are formed in the pocket. The webs connect the side parts to one another and are orientated from an opening side of the filter bag in the direction of the bottom edge. The flexible material web is alternately connected—at least in portions—to one of the side parts in each case in weld portions. The weld portions are delimited by at least one weld across the direction of flow.