PTFE Air Filter Medium Structure for Low Pressure Loss
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Solution Overview
Problem
Existing air filter media, particularly those with PTFE porous membranes, face challenges in suppressing pressure loss due to clogging and structural resistance when pleated, making it difficult to maintain low pressure loss in air filter units.
Innovation Solution
A filter medium comprising a pre-collection layer, a principal collection layer, an air-permeable cover layer, and an air-permeable support layer, where the pre-collection layer is made with non-woven fibers of specific diameter and weight, the principal collection layer uses a PTFE porous membrane with controlled stretching and lubrication, and the air-permeable cover layer reduces deformation and structure resistance.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Reliability
If a PTFE porous membrane with denser fiber structure is used, then dust collection efficiency is improved, but pressure loss increases quickly due to clogging
Solution Approach 1:
The filter medium is divided into multiple functional layers: a PTFE porous membrane layer for high-efficiency dust collection and a fibrous air-permeable porous medium layer for pre-filtration and maintaining air permeability. This segmentation allows each layer to perform its specific function optimally, preventing the PTFE layer from clogging quickly while maintaining high dust collection efficiency.
Solution Approach 2:
The invention uses a composite structure combining PTFE porous membrane material with a fibrous air-permeable porous medium. The PTFE layer provides superior dust collection efficiency while the fibrous medium layer provides high air permeability and resistance to clogging, creating a composite filter medium that balances both dust collection efficiency and pressure loss characteristics.
2Area of stationary object
If pleats processing is applied to the filter medium, then the surface area is increased, but structure resistance increases causing higher pressure loss in air filter unit
Solution Approach 1:
The air-permeable cover layer is specifically positioned on the upstream side of the air flow where it directly contacts the pleated surface. This layer has optimized properties (fiber diameter 3-20 μm, weight per unit area 10-50 g/m²) to reduce structure resistance at the critical pleated regions, allowing the filter medium to maintain low pressure loss even when pleated to increase surface area.
3Reliability
If fiber diameter of air-permeable support medium is reduced, then dust collection efficiency is improved, but pressure loss in support medium increases
Solution Approach 1:
The invention optimizes the fiber diameter parameter of the air-permeable cover layer to be 3-20 μm, which is larger than conventional filters. This parameter change reduces the density of the fibrous structure, maintaining high air permeability and low pressure loss in the support medium while still achieving effective dust collection when combined with the PTFE porous membrane layer.
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 filter medium effectively suppresses pressure loss in air filter units, maintaining a life span comparable to glass fiber filters while ensuring efficient dust collection, with reduced structure resistance and pressure loss, even under high dust collection loads.
Implementation Method 1
a porous membrane (hereinbelow, referred to as PTFE porous membrane) consisting of polytetrafluoroethylene (hereinbelow, referred to as PTFE) is used as a dust collecting filter
Implementation Method 2
the PTFE porous membrane has higher dust collection efficiency when comparison is made at the same pressure loss
Implementation Method 3
a fibrous air-permeable porous medium, in which the fibrous air-permeable porous medium has a fiber diameter ranging from 1 to 15 μm, a porosity of 70% or more
Data Source
Figure 1A~1B
Figure 2~3B
Figure 4~5B
AI summary
A filter medium for an air filter unit for collecting dust from an airflow comprising: a pre-collection layer for collecting a part of the dust in the airflow; a principal collection layer that includes a porous polytetrafluoroethylene film and is positioned on a downstream side of the air flow relative to the pre-collection layer to collect dust that passes through the pre-collection layer; and a air-permeable cover layer that is positioned in the outermost surface layer on an upstream side of the air flow to allow dust in the air flow to pass therethrough and to suppress deformation of the surface of the filter medium for an air filter caused by pressing force from an outside.