Air Filter Unit With Differential Thermal Expansion Separators
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Solution Overview
Problem
Air filters used in high-temperature applications experience sealability issues due to thermal expansion differences between separators and the filter frame, leading to dust leakage and reduced functionality over time.
Innovation Solution
The air filter unit incorporates zigzag-shaped pleated filter media with metal space-supporting members, where the linear expansion coefficients of side portion separators are adjusted to match or exceed those of the filter frame, using materials like stainless steel and aluminum alloys, and a fiber sealing material to maintain sealability across thermal cycles.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Temperature
If aluminum or aluminum alloy separators are used in high-temperature air filters, then heat resistance and work efficiency are improved, but the separators contract during thermal cycles causing sealability deterioration
Solution Approach 1:
The patent changes the material parameter (linear expansion coefficient) of the separators from aluminum/aluminum alloy to stainless steel, which has a linear expansion coefficient closer to that of the filter frame body. This parameter change ensures that the separators and frame body expand and contract at similar rates during thermal cycles, preventing the contraction-induced gaps that compromise sealability while maintaining heat resistance.
Solution Approach 2:
The patent applies homogeneity by selecting separators made of stainless steel that have thermal expansion characteristics matching those of the stainless steel filter frame body. This creates a homogeneous thermal expansion behavior across the entire filter assembly, ensuring uniform expansion and contraction during temperature cycles, thereby maintaining consistent sealability throughout the structure.
2Stability of the object's composition
If separators with high linear expansion coefficient are used, then thermal expansion at high temperature is accommodated, but contraction during cooling causes gaps and dust leakage
Solution Approach 1:
The patent modifies the linear expansion coefficient parameter of the separators by changing the material from aluminum to stainless steel. This parameter adjustment ensures that the separators' expansion and contraction behavior matches that of the filter frame body, allowing the separators to maintain their spacing function during thermal cycles without creating gaps that would compromise sealability.
3Reliability
If adhesive bonding is used to fix filter medium to frame body, then initial sealability is achieved, but adhesive layer damages and cracks due to thermal history
Solution Approach 1:
The patent changes the bonding mechanism from adhesive bonding to mechanical support, where stainless steel separators provide structural support to the filter medium through their rigidity and thermal expansion matching with the frame. This eliminates the adhesive layer that would otherwise crack and fail under repeated thermal cycling, thereby extending the service life while maintaining sealability.
Solution Approach 2:
The patent replaces the chemical bonding system (adhesive) with a mechanical support system (stainless steel separators). The separators mechanically hold the filter medium in place and maintain the required spacing, eliminating the need for adhesive layers that are vulnerable to thermal degradation, thus improving durability under thermal cycling conditions.
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 stabilizes the air filter's performance over multiple thermal cycles, ensuring effective dust collection and maintaining seal integrity by minimizing separator contraction and maintaining contact with the fiber sealing material.
Implementation Method 1
the linear expansion coefficients of the space-supporting members are equal to or more than a linear expansion coefficient of the filter frame body. The linear expansion coefficients of first space-supporting members provided in side portion regions including both side portions are smaller than a linear expansion coefficient of second space-supporting members provided in a central portion region
Data Source
Figure 1
Figure 2A~2B
Figure 3
AI summary
The air filter unit has a pleated filter medium with a zigzag shape in which a fibrous filter medium has been folded multiple times. The coefficients of linear expansion of the separators (space-supporting members) provided in each of the multiple folded spaces of the pleated filter medium are equal to or greater than the coefficient of linear expansion of the metal filter frame of the filter unit. Moreover, among said separators, the coefficient of linear expansion of each of separators that are provided at the side regions, which comprise the two side sections located at the outermost ends of the pleated filter medium in a second direction that is orthogonal to the direction of folding of the pleated filter medium (the first direction), is smaller than the coefficient of linear expansion of a separators provided in the central region that is flanked by the side regions.