Filter element for an extractor hood
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Solution Overview
Problem
Existing expanded metal filters in extractor hoods suffer from high pressure loss and low efficiency due to large openings, leading to increased energy consumption and unit costs, while also being prone to rough edges and corrosion.
Innovation Solution
A filter element with multiple layers of plastic material, featuring fixed-size small openings and cover layers for mechanical protection and air permeability, which reduces pressure loss and enhances separation efficiency.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Loss of energy
If expanded metal filters with large openings are used, then pressure loss is reduced per layer, but filter efficiency is low due to large mesh size
Solution Approach 1:
The filter element is divided into multiple filter layers (at least two layers) with different mesh sizes. The first filter layer has a first mesh size and the second filter layer has a second mesh size that is smaller than the first mesh size. This segmentation allows each layer to perform different filtering functions, with the coarser first layer capturing larger particles and the finer second layer capturing smaller particles, thereby achieving high filter efficiency while maintaining acceptable pressure loss characteristics.
Solution Approach 2:
The solution transitions from a single-layer filter design to a multi-layer filter design, adding the dimension of layer stacking. By arranging filter layers with different mesh sizes in sequence, the system achieves both low pressure loss (from the coarser first layer) and high filter efficiency (from the combined effect of multiple layers with progressively finer mesh sizes).
2Reliability
If more layers are added to increase filter efficiency, then grease filtration performance improves, but unit cost and weight increase significantly
Solution Approach 1:
Different filter layers are designed with different local qualities - specifically, different mesh sizes tailored to specific filtering needs. The first filter layer uses a coarser mesh for capturing larger grease particles, while the second filter layer uses a finer mesh for capturing smaller particles. This localized optimization of mesh size in different layers achieves high grease filtration performance without requiring excessive numbers of layers, thereby controlling unit cost.
Solution Approach 2:
The invention changes the parameter of mesh size across different filter layers. By systematically varying the mesh size parameter (first mesh size larger than second mesh size), the filter achieves progressive filtration efficiency enhancement. This parameter change approach allows optimization of grease filtration performance while avoiding the need for many uniform layers, thus controlling manufacturing cost.
3Loss of energy
If expanded metal is used for filter layers, then large openings minimize pressure drop, but rough edges from manufacturing increase pressure loss
Solution Approach 1:
The invention replaces expensive expanded metal filters with disposable plastic filter layers. These plastic layers can be manufactured with smooth edges using injection molding or extrusion processes, eliminating the rough edge problem inherent in scratched and stretched expanded metal. The smooth edges reduce turbulence and pressure loss while maintaining the large opening benefit for minimal pressure drop.
Solution Approach 2:
The invention substitutes the mechanical expanded metal manufacturing process (scratching and stretching that creates rough edges) with a plastic forming process (injection molding or extrusion) that produces smooth edges inherently. This mechanical substitution eliminates the harmful rough edges while preserving the large opening structure needed for minimal pressure drop.
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 solution minimizes pressure loss, increases filter efficiency, and provides chemical resistance and improved visual appeal, while being cost-effective and easier to produce and maintain.
Implementation Method 1
The air speed increases due to the blocking effect of the screen, and the inertial effects become more dominant due to the higher speeds
Implementation Method 2
The filter element minimizes pressure loss
Data Source
Figure 1
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AI summary
The invention relates to a filter element for an extractor hood, which has a filter mat with at least one filter layer. The filter element is characterized in that the filter layer consists of a plastic material and has openings, the size of which is fixed, the filter mat being surrounded by a cover layer which is arranged essentially parallel to the surface of the filter mat and in front of and behind the filter mat in the air flow direction and which is at least partially permeable to air are.