Filter material and filter unit
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Solution Overview
Problem
Filter media with porous PTFE membranes face a trade-off between durability and air permeability, as enhancing durability to facilitate dust removal can lead to a significant decrease in air permeability, and existing methods of cleaning can damage the membranes.
Innovation Solution
A filter medium configuration with alternating layers of PTFE membranes and air-permeable support members, bonded using thermal lamination, where the embossed non-woven fabrics with an appropriate embossed area ratio ensure high bond strength and maintain air permeability.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Reliability
If the bond strength between the porous PTFE membrane and the support member is enhanced or the thickness of the porous PTFE membrane is increased, then the durability of the filter medium is improved, but the air permeability significantly decreases
Solution Approach 1:
The filter medium is segmented into multiple thin porous PTFE membrane layers (first, second, and third porous PTFE membranes) with support members positioned between them. This segmentation allows each thin membrane layer to maintain high air permeability while the cumulative structure provides sufficient durability through the distributed bonding across multiple interfaces with support members.
Solution Approach 2:
The filter medium employs a composite structure combining porous PTFE membranes with air-permeable support members (such as non-woven fabrics). This composite material approach allows the thin porous PTFE membranes to provide filtration functionality with high air permeability, while the support members provide structural reinforcement to enhance durability without significantly impeding air flow.
2Ease of operation
If the porous PTFE membrane is exposed to high pressure from air stream or water stream for dust removal, then the dust can be removed from the surface, but the porous PTFE membrane may be broken or separated from the support member
Solution Approach 1:
Air-permeable support members are positioned between the porous PTFE membranes to provide beforehand cushioning and mechanical reinforcement. These support members act as protective layers that distribute and absorb the high pressure冲击力 during air or water stream cleaning, preventing the thin porous PTFE membranes from breaking or separating while still allowing dust removal to proceed effectively.
3Productivity
If the porous PTFE membrane is made very thin to maintain air permeability, then the air flow resistance is reduced, but the membrane becomes vulnerable to damage from cleaning processes
Solution Approach 1:
The filter medium divides the filtration function across multiple thin porous PTFE membrane layers rather than using a single thick membrane. Each thin layer maintains high air permeability, while the distributed arrangement with support members in between provides cumulative structural strength and durability resistant to cleaning processes.
Solution Approach 2:
Air-permeable support members serve as intermediary elements positioned between the porous PTFE membranes. These intermediaries provide mechanical support and protection to the thin porous membranes, distributing stress during cleaning operations and preventing direct damage to the vulnerable membrane surfaces while maintaining overall air permeability.
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 configuration allows for improved durability in dust removal without a significant decrease in air permeability, as the embossed non-woven fabrics provide sufficient bond strength while minimizing pressure loss across the filter medium.
Implementation Method 1
a porous polytetrafluoroethylene (PTFE) membrane
Implementation Method 2
bonded to one another in an alternating order by thermal lamination
Data Source
Figure 1
Figure 2A~2C
Figure 3A~3B
AI summary
A filter medium (20) includes a first porous PTFE (11) membrane, a first air-permeable support member (12), a second porous PTFE membrane (13), and a second air-permeable support member (14). A surface of the filter medium (20) is formed by the first porous PTFE membrane (11). A bond strength (A1), as measured by a 180° peel test, between the first porous PTFE membrane (11) and the first air-permeable support member (12) is higher than 1.2 N/25 mm. The first air-permeable support member (12) is an embossed non-woven fabric having one or more recessed portions and one or more projecting portions. A ratio of the area of the recessed portion or the total area of the recessed portions to the area of the embossed non-woven fabric serving as the first air-permeable support member (12) is more than 15%.