Air Filter Frame Segmentation for Round Channel Integration

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Solution Overview

Problem

Existing air filter manufacturing methods are inefficient for producing filters with round cross-sections, leading to increased material loss and difficulty in automation, especially when trying to mount filters in round channels or passages.

Innovation Solution

A method involving a four-sided filter frame made of elongated distance elements, which is cut to form a circular shape, allowing for reduced material loss and efficient production, using a punching tool to create a round filter frame with equally divided flexible fibers, and a snap-in connection or attachment mechanism for secure placement within a tubular casing.

Engineering Contradictions & Design Principles

VSEngineering Contradiction Analysis

1Adaptability or versatility

If a round filter frame is manufactured by rolling up flexible band with distance elements, then the filter can be mounted in round channels, but the flow resistance increases in the centre area and manufacturing automation becomes difficult

Engineering Contradiction:
Improvemounting adaptability to round channelsVSAvoidmanufacturing automation capability
Core Design Contradiction:
Adaptability or versatilityVSProductivity

Solution Approach 1:

The filter frame is segmented into multiple straight distance elements arranged side by side to form a rectangular frame, which is then cut into a circular shape. This segmentation allows each distance element to be manufactured separately using standardized processes, enabling automation while achieving circular mounting compatibility.

Inventive Principle:
Principle #1Segmentation

Solution Approach 2:

Instead of forming a round filter frame by rolling up a flexible band (as in prior art), the invention inverts the approach by assembling straight distance elements into a rectangular frame and then cutting it into a circular shape. This reversal of the manufacturing sequence eliminates the need for complex rolling operations and enables automated production.

Inventive Principle:
Principle #13The other way round (Inversion)

2Ease of manufacture

If a four-sided filter frame with rectangular distance elements is used, then manufacturing is simplified and automation is easier, but the filter cannot be mounted in round channels or passages

Engineering Contradiction:
Improvemanufacturing simplicity and automationVSAvoidmounting compatibility with round channels
Core Design Contradiction:
Ease of manufactureVSAdaptability or versatility

Solution Approach 1:

The filter frame is preliminarily assembled as a rectangular configuration using straight distance elements, which simplifies manufacturing and enables automation. The circular shape is then achieved in a subsequent cutting step, thereby preliminarily establishing the manufactured form before final adaptation to round channels.

Inventive Principle:
Principle #10Preliminary action

Solution Approach 2:

The filter frame is divided into multiple straight distance elements that can be manufactured using standardized automated processes. These segmented elements are then assembled into a rectangular frame and cut into a circular shape, combining manufacturing simplicity with mounting versatility.

Inventive Principle:
Principle #1Segmentation

3Shape

If the flexible fibres are rolled up with increasing number per area unit towards the centre, then the round filter frame shape is achieved, but the flow resistance becomes non-uniform with larger resistance in the centre area

Engineering Contradiction:
Improvecircular filter frame shapeVSAvoidflow resistance uniformity
Core Design Contradiction:
ShapeVSManufacturing precision

Solution Approach 1:

The distance elements are equipped with uniformly distributed attachment points along their entire length, ensuring that flexible fibres are attached with consistent spacing and density across all locations. This local uniformity in attachment quality compensates for the circular shape, maintaining uniform flow resistance throughout the filter frame.

Inventive Principle:
Principle #3Local quality

Solution Approach 2:

The filter frame is constructed with homogeneous distribution of distance elements and attachment points, ensuring uniform flexible fibre spacing across the entire circular perimeter. This homogeneous structure eliminates the non-uniform fibre density that would otherwise occur in rolled-up constructions, achieving both circular shape and uniform flow resistance.

Inventive Principle:
Principle #33Homogeneity

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

Enables the production of air filters with reduced material waste and improved manufacturing efficiency, allowing for seamless integration into round channels while maintaining uniform fiber distribution and effective air filtration.

Implementation Method 1

The filter frame is cut such that a filter frame with a substantially circular contour shape is obtained

Methodology Applied
Scientific EffectCutting:

Implementation Method 2

a filter body with a plurality of curtains of electrostatically chargeable fibres which separate particles from the air both by means of mechanical and electrostatic action

Methodology Applied
Scientific EffectElectrostatic action: Electrostatics

Implementation Method 3

separate particles from the air both by means of mechanical and electrostatic action

Methodology Applied
Scientific EffectMechanical filtration: Filter (physical)

Implementation Method 4

a snap-in connection or attachment mechanism for secure placement within a tubular casing

Methodology Applied
Scientific EffectMechanical fastening: Mechanical Fastener

Data Source

PatentEP1981609B1An air filter and a method for manufacturing such an air filter
Publication Date: 2014.09.17 ZEHNDER GROUP NORDIC
  • EP1981609B1 patent drawingFigure 1~2
  • EP1981609B1 patent drawingFigure 3~5
  • EP1981609B1 patent drawingFigure 6~7

AI summary

The present invention relates to an air filter and a method for manu¬ facturing of such filter. The air filter comprises a filter frame (20) which comprises a plurality of side by side mounted elongated dis¬ tance elements (11 ) which form passages for air, and a filter body, which comprises electrically chargeable fibres which are attached to distance elements (11 ) such that the fibres obtain an extension from the filter body (20) to a position located at a distance from and downstream the filter body (20) with respect to the intended flow direction of the air through the air filter. The filter frame (20) has a substantially round contour shape in that two peripheral and diamet¬ rically opposite distance elements (11 ) are shorter than the remain¬ ing distance elements (11 ) and that the side by side mounted dis- tance elements (11 ) have a length which increases successively in direction towards the centre of the filter frame (20).