Laminated PTFE Filter for Transport Housing Pressure
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Solution Overview
Problem
The challenge is to create an internal pressure adjustment member with high air permeability, even when the differential pressure between the inside and outside of a housing is small, and to prevent damage and reduction in air permeability due to soil and mud exposure, especially for electrical components in transport equipment.
Innovation Solution
An internal pressure adjustment member is designed with a laminated structure featuring a net-like or mesh-like support layer and two porous polytetrafluoroethylene (PTFE) membranes, where both PTFE membranes are exposed and have an average pore diameter of 2.0 μm or more, and the filter portion has a thickness of 140 μm or less and a density of 0.60 g/cm³ or less, ensuring high air permeability and resistance to soil and mud adhesion and penetration.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Productivity
If the air permeability of the internal pressure adjustment member is increased to discharge water vapor quickly, then the water vapor discharge performance is improved, but the member becomes more susceptible to damage and air permeability reduction from soil and mud
Solution Approach 1:
The internal pressure adjustment member uses a composite structure consisting of a porous PTFE membrane layer and a porous support layer. The PTFE membrane provides excellent waterproof and dustproof properties with controlled air permeability, while the porous support layer provides mechanical strength and resistance to damage from soil and mud. This composite material approach allows the member to maintain high air permeability for water vapor discharge while being protected against external contaminants and physical damage.
2Reliability
If a single porous PTFE membrane is used to ensure waterproof and dustproof properties, then the protection against foreign matter is improved, but the air permeability is reduced making it difficult to discharge water vapor
Solution Approach 1:
The internal pressure adjustment member is segmented into two functional layers: a porous PTFE membrane layer and a porous support layer. The PTFE membrane layer (thickness 10-50 μm) provides the waterproof and dustproof barrier with controlled pore structure, while the porous support layer (thickness 50-200 μm) provides mechanical support and enhanced air permeability. This segmentation allows each layer to optimize its specific function, achieving both protection and breathability.
3Ease of manufacture
If the internal pressure adjustment member is attached to the outer surface of the housing after assembly to improve workability, then the ease of assembly is improved, but the member is exposed to soil and mud causing damage and reduced air permeability
Solution Approach 1:
The porous support layer acts as a protective cushion layer positioned between the external environment (soil and mud) and the delicate porous PTFE membrane. This prior cushioning structure absorbs and distributes mechanical stresses from external contaminants, preventing direct contact and damage to the PTFE membrane. The support layer's porous structure allows air permeability while providing physical protection, enabling the member to be attached to the outer surface for ease of assembly without compromising durability.
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 configuration enhances air permeability while maintaining structural strength, inhibiting damage from soil and mud, and ensures effective discharge of water vapor, maintaining excellent discharge properties over time.
Implementation Method 1
the excellent waterproof and dustproof properties of the porous PTFE membrane
Implementation Method 2
absorption of ambient water vapor by the housing is inevitable. The absorbed water vapor is released by heat from a heat source inside the housing or heat from the outside such as sunlight
Implementation Method 3
a differential pressure that can be generated between the inside and the outside of the housing and that is the driving force of the discharge is normally small
Data Source
Figure 1~2
Figure 3A~3B
Figure 4A~4B
AI summary
Provided is an internal pressure adjustment member to be attached to an outer surface of a housing, the member having high air permeability even when a differential pressure that can be generated between the inside and the outside of a housing to which the internal pressure adjustment member is attached is small, and inhibiting damage to the member and a reduction in the air permeability of the member due to coming soil and mud. The internal pressure adjustment member includes: a filter portion including a net-like or mesh-like support layer and first and second porous polytetrafluoroethylene (PTFE) membranes laminated on the support layer such that the support layer is interposed therebetween, the first porous PTFE membrane being exposed on one surface of the filter portion, the second porous PTFE membrane being exposed on another surface of the filter portion; and an adhesive portion, formed on the one surface of the filter portion, for attaching the filter portion to the outer surface of the housing. The first porous PTFE membrane and the second porous PTFE membrane each have an average pore diameter of 2.0 pm or more, the filter portion has a thickness of 140 pm or less, and the filter portion has a density of 0.60 g/cm3 or less.