Over-Injected Plastic Porthole Door for Lighter Washer Assembly

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Solution Overview

Problem

Front-loading laundry washing machines' porthole doors are expensive and heavy due to the use of annealed glass, and existing plastic alternatives do not adequately address cost and weight reduction while maintaining structural integrity and aesthetics.

Innovation Solution

A porthole door design featuring a basin-shaped body made of transparent plastic with an over-injected opaque inner annular frame, produced via a single injection molding process, which simplifies assembly, reduces material costs, and enhances aesthetics through contrasting transparent and opaque elements.

Engineering Contradictions & Design Principles

VSEngineering Contradiction Analysis

1Illumination intensity

If annealed glass is used for the porthole door body, then transparency and safety are improved, but weight and production cost increase

Engineering Contradiction:

ImprovetransparencyVSAvoiddoor weight

Core Design Contradiction:

Illumination intensityVSWeight of moving object

Solution Approach 1:

The patent changes the material parameter from annealed glass to transparent plastic, maintaining the transparency function while significantly reducing weight. The plastic material allows for thinner wall sections and lighter construction while preserving optical properties.

Inventive Principle:

Principle #35Parameter changes

Solution Approach 2:

The patent employs a cheaper plastic material instead of expensive annealed glass, reducing production costs while maintaining the required transparency and safety functions for the porthole door.

Inventive Principle:

Principle #27Cheap short-living objects (Disposable)

2Illumination intensity

If annealed glass is used for the porthole door body, then transparency is improved, but production cost increases

Engineering Contradiction:

ImprovetransparencyVSAvoidproduction cost

Core Design Contradiction:

Illumination intensityVSEase of manufacture

Solution Approach 1:

The patent changes the material parameter from annealed glass to transparent plastic, maintaining the transparency function while significantly reducing production costs. The plastic material is cheaper to source and process.

Inventive Principle:

Principle #35Parameter changes

Solution Approach 2:

The patent employs a cheaper plastic material instead of expensive annealed glass, reducing production costs while maintaining the required transparency and safety functions for the porthole door.

Inventive Principle:

Principle #27Cheap short-living objects (Disposable)

3Weight of moving object

If transparent plastic is used for the porthole door body, then weight and cost are reduced, but structural integrity and aesthetics may be compromised

Engineering Contradiction:

Improvedoor weightVSAvoidstructural integrity

Core Design Contradiction:

Weight of moving objectVSStrength

Solution Approach 1:

The patent creates a composite structure by integrating the transparent plastic door body with an opaque inner annular frame. This composite design allows the plastic to provide transparency and weight reduction while the frame reinforces structural integrity and provides mounting points for hinges and handles.

Inventive Principle:

Principle #40Composite materials

Solution Approach 2:

The patent segments the door into two functional parts: a transparent plastic body for visibility and weight reduction, and an opaque plastic frame for structural support and hardware mounting. This segmentation allows each material to optimize its specific function.

Inventive Principle:

Principle #1Segmentation

4Ease of manufacture

If a single injection molding process is used, then manufacturing complexity is reduced, but achieving both transparent and opaque sections in one piece may be difficult

Engineering Contradiction:

Improvemanufacturing complexityVSAvoidmolding precision

Core Design Contradiction:

Ease of manufactureVSManufacturing precision

Solution Approach 1:

The patent merges the transparent door body and opaque frame into a single integrated component produced by one injection molding process. The molding apparatus switches between transparent and opaque plastic materials during a single cycle, creating a unified part with both transparency and structural reinforcement features.

Inventive Principle:

Principle #5Merging (Combining)

Solution Approach 2:

The patent creates a composite structure by integrating the transparent plastic door body with an opaque inner annular frame, produced in a single injection molding process that switches between materials, achieving both aesthetic and structural requirements.

Inventive Principle:

Principle #40Composite materials

Data Source

PatentEP2243874B1Porthole door for laundry washing machines and household appliance provided with said porthole door

Publication Date: 2012.07.04 ELECTROLUX HOME PROD CORP NV

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AI summary

Porthole door (1) for laundry washing machines (2) and similar consisting of a substantially basin-shaped body (11) which is made of transparent or semi-transparent plastic material, and is provided with an outer peripheral flange (11a) having a substantially U-shaped transversal cross section, and of an inner annular frame (12) which is made of an opaque plastic material, and is permanently fixed into the annular seat (11') formed by said outer peripheral flange (11a); the outer peripheral flange (11a) being realized in one piece with the rest of basin-shaped body (11) via an injection molding process, so as to form a unique plastic shell (11); said unique plastic shell (11) and said inner annular frame (12) being over-injected one on the other during the same injection molding process.