Ring Filter Element Inner Contour for Precise Angular Positioning

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Solution Overview

Problem

Existing ring filter elements are prone to damage during handling due to manufacturing-related deviations from rotational symmetry, which can lead to incorrect orientation and potential mechanical damage to the pleat edges, affecting the alignment and performance of air filtration systems, particularly in applications like combustion engines and fuel cells.

Innovation Solution

A ring filter element design featuring a pleat spread on the inner surface with aligned recesses in the open end disc, allowing for unambiguous angular positioning and minimizing deformation or tearing during handling, while ensuring minimal rotational play, thus protecting the pleat edges and facilitating correct alignment within the filtration system.

Engineering Contradictions & Design Principles

VSEngineering Contradiction Analysis

1Area of stationary object

If external pleating is used for the filter medium body, then the filtration surface area is increased, but the pleat edges are prone to mechanical damage during handling

Engineering Contradiction:
Improvefiltration surface areaVSAvoidmechanical strength of pleat edges
Core Design Contradiction:
Area of stationary objectVSStrength

Solution Approach 1:

The patent inverts the conventional external pleating approach by implementing internal pleating within the filter medium body. The pleats are formed inside the hollow cylindrical structure rather than on the outer surface, which protects them from mechanical damage during handling while still providing increased filtration surface area. The pleat edges are contained within the filter medium body and cannot be easily damaged by external forces.

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

2Ease of manufacture

If manufacturing-related deviations from rotational symmetry occur, then production is simplified, but the ring filter element cannot be correctly aligned in the housing

Engineering Contradiction:
Improveproduction simplicityVSAvoidrotational alignment precision
Core Design Contradiction:
Ease of manufactureVSManufacturing precision

Solution Approach 1:

The patent introduces asymmetric features into the otherwise rotationally symmetric ring filter element. Specifically, one or more pleat spreads are created on the inner surface of the filter medium body, and corresponding asymmetric recesses are formed in the open end disk. These asymmetric features serve as alignment references that enable correct rotational positioning in the housing while maintaining relatively simple manufacturing processes.

Inventive Principle:
Principle #4Asymmetry

Solution Approach 2:

The patent introduces engagement elements as intermediaries between the ring filter element and the housing. These engagement elements interact with the asymmetric recesses and pleat spreads to enforce the predetermined rotational position. The engagement elements mediate the alignment process, allowing the filter element to be correctly positioned without requiring complex manufacturing precision throughout the entire component.

Inventive Principle:
Principle #24Intermediary (Mediator)

3Ease of manufacture

If the ring filter element is made rotationally symmetrical, then manufacturing is easier, but alignment in the housing becomes ambiguous

Engineering Contradiction:
Improvemanufacturing easeVSAvoidalignment clarity
Core Design Contradiction:
Ease of manufactureVSEase of operation

Solution Approach 1:

The patent maintains overall rotational symmetry for ease of manufacture but introduces localized asymmetric features (pleat spreads and corresponding recesses) that provide unambiguous alignment information. This approach allows the majority of the filter element to be manufactured using simple rotational forming processes while the asymmetric features guide correct installation orientation.

Inventive Principle:
Principle #4Asymmetry

4Manufacturing precision

If engagement elements are added for positioning, then alignment precision is improved, but device complexity increases

Engineering Contradiction:
Improveangular positioning precisionVSAvoidstructural complexity
Core Design Contradiction:
Manufacturing precisionVSDevice complexity

Solution Approach 1:

The patent merges the engagement elements with existing components of the ring filter element. The engagement elements are integrated into the open end disk and the pleat spreads, rather than being separate additional components. This merging approach provides precise angular positioning while minimizing the increase in overall device complexity.

Inventive Principle:
Principle #5Merging (Combining)

Solution Approach 2:

The engagement elements serve multiple functions: they provide angular positioning, prevent rotational play, and guide the installation process. By making these elements multi-functional, the patent achieves precise alignment without adding proportional complexity to the device structure.

Inventive Principle:
Principle #6Universality (Multi-functionality)

Data Source

PatentEP4661989B1Ring filter element with radially inner engagement contour for angular positioning
Publication Date: 2026.04.08 MANN HUMMEL GMBH
  • EP4661989B1 patent drawingFigure 1
  • EP4661989B1 patent drawingFigure 2
  • EP4661989B1 patent drawingFigure 3

AI summary

The invention relates to a ring filter element comprising a filter medium body in the form of a bellows which has, radially inwards, at least one fold that is spread out and adjoins an open end disc. The open end disc has at least one recess, said recess and spread-out fold being arranged so as to overlap with each other. The filter medium body is sealed by a closed end disc at the axial end facing away from the open end disc. When the ring filter element is used in a filter device, an engagement element engages into a spread-out fold and/or into the recess. The engagement element can be formed on a filter housing or on another ring filter element of the filter device. Thus, the angular position of the ring filter element is fixed with respect to the filter housing or the other ring filter element.