One-Piece Filter Element Using Thermoplastic Foam Injection Molding

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Solution Overview

Problem

Existing methods for producing filter elements in household appliances require multiple processes and are not suitable for efficient production of fine mesh structures, particularly in a single step.

Innovation Solution

A method using thermoplastic foam injection molding to create a one-piece filter element with a grid structure, where the filter is formed first, followed by the frame, utilizing a blowing agent to ensure simultaneous filling and integration with a support frame, optimizing the grid structure and frame transition.

Engineering Contradictions & Design Principles

VSEngineering Contradiction Analysis

1Productivity

If multiple separate processes are used to produce filter elements and frames, then manufacturing flexibility is maintained, but production time and complexity increase

Engineering Contradiction:
Improveproduction timeVSAvoidprocess complexity
Core Design Contradiction:
ProductivityVSDevice complexity

Solution Approach 1:

The patent combines the production of the filter element and the frame into a single injection molding process. The filter element is first molded in a first cavity, then the same injection molding machine forms the frame in a second cavity without removing the filter element. This merging of operations eliminates the need for separate production processes and intermediate handling, directly reducing production time and process complexity.

Inventive Principle:
Principle #5Merging (Combining)

2Manufacturing precision

If fine mesh structures are produced using traditional methods, then manufacturing capability is maintained, but structural weaknesses and production inefficiency occur

Engineering Contradiction:
Improvegrid structure qualityVSAvoidproduction efficiency
Core Design Contradiction:
Manufacturing precisionVSProductivity

Solution Approach 1:

The patent employs injection molding parameters and material properties that enable the formation of fine mesh structures with high precision. By controlling the injection pressure, temperature, and material flow characteristics, the process achieves accurate reproduction of fine grid patterns while maintaining production efficiency. The use of appropriate polymer materials with suitable viscosity and cooling rates ensures structural integrity of thin web elements.

Inventive Principle:
Principle #35Parameter changes

3Strength

If the filter and frame are produced separately and assembled, then manufacturing flexibility is maintained, but assembly points and structural weaknesses are created

Engineering Contradiction:
Improvestructural integrityVSAvoidassembly complexity
Core Design Contradiction:
StrengthVSDevice complexity

Solution Approach 1:

The patent integrates the filter element and frame into a single molded part produced in one continuous process. The filter element remains in the first cavity while the frame is formed in a second cavity, and both are ejected as an integrated assembly. This eliminates separate assembly operations and potential weak points at joining locations, directly improving structural integrity while reducing assembly complexity.

Inventive Principle:
Principle #5Merging (Combining)

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 a filter element with a fine grid structure in a single process, reducing material and energy costs, minimizing structural weaknesses, and achieving uniform pressure distribution, while allowing for thinner and larger grid structures with improved flowability.

Implementation Method 1

thermoplastic foam injection molding of a melt of a thermoplastic plastic containing a blowing agent

Methodology Applied
Scientific EffectFoaming: Foam

Data Source

PatentEP4295934B1Domestic appliance with filter element and method for producing the filter element by means of thermoplastic foam injection moulding
Publication Date: 2025.07.09 BSH HAUSGERATE GMBH
  • EP4295934B1 patent drawingFigure 1
  • EP4295934B1 patent drawingFigure 2
  • EP4295934B1 patent drawingFigure 3(a)~3(c)

AI summary

The invention relates to a household appliance with a one-piece filter element 1 made of a plastic material, wherein the one-piece filter element 1 comprises a filter 3 with a round contour 9 surrounded by a frame 2, and the one-piece filter element 1 is obtainable by thermoplastic foam injection molding of a blowing agent-containing melt of a thermoplastic material. The invention further relates to a method for manufacturing the one-piece filter element 1.