Thermally Conductive Plastic Control Knob for Metal-Like Cool Touch

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Solution Overview

Problem

Existing control knobs for household appliances, particularly those made of plastic, fail to replicate the visual and tactile experience of metal knobs, as they lack the thermal conductivity that gives metal its characteristic 'cool touch' and are often limited by cost or mechanical stress concerns.

Innovation Solution

A plastic control element filled with a material having higher thermal conductivity than the base plastic, such as metallic powders or ceramics, to enhance both the visual and tactile metal-like experience while being cost-effective and durable.

Engineering Contradictions & Design Principles

VSEngineering Contradiction Analysis

1Illumination intensity

If a plastic control element is coated with a thin metallic layer, then the visual impression is improved, but the tactile feel remains plastic-like and does not convey the cold metal sensation

Engineering Contradiction:
Improvevisual impressionVSAvoidtactile feel
Core Design Contradiction:
Illumination intensityVSEase of operation

Solution Approach 1:

The patent applies composite materials by combining plastic with metal fillers (such as aluminum powder, copper powder, or stainless steel powder) to create a filled plastic material. This composite structure provides both the visual appearance and the thermal conductivity characteristics of metal, resolving the contradiction between visual impression and tactile feel.

Inventive Principle:
Principle #40Composite materials

Solution Approach 2:

The patent changes the thermal conductivity parameter of the plastic material by adding metal fillers. The filled plastic achieves thermal conductivity values between 0.5-30 W/mK (preferably 2-10 W/mK), which is significantly higher than conventional plastic (0.2-0.3 W/mK) and sufficient to create the cold metal sensation on touch while maintaining the benefits of plastic.

Inventive Principle:
Principle #35Parameter changes

2Ease of operation

If aluminum-zinc alloy toggles are used, then the metal feel is excellent, but the permissible temperature limit is too low for many household appliances

Engineering Contradiction:
Improvemetal feelVSAvoidpermissible temperature limit
Core Design Contradiction:
Ease of operationVSTemperature

Solution Approach 1:

The patent changes the material composition to filled plastic with metal fillers, which can achieve thermal conductivity values (0.5-30 W/mK) that simulate metal feel while maintaining the high temperature resistance of plastic. This allows the control element to withstand temperatures up to 200°C or higher, unlike aluminum-zinc alloys.

Inventive Principle:
Principle #35Parameter changes

Solution Approach 2:

The patent uses composite materials consisting of plastic matrix combined with metal fillers (aluminum powder, copper powder, stainless steel powder, etc.). This composite structure combines the thermal conductivity of metal fillers with the temperature resistance of plastic, resolving the contradiction between metal feel and temperature limit.

Inventive Principle:
Principle #40Composite materials

3Ease of manufacture

If plastic control elements are used, then cost is reduced and mechanical stress resistance is improved, but the thermal conductivity is insufficient to provide a metal-like cold touch

Engineering Contradiction:
Improvecost and durabilityVSAvoidthermal conductivity
Core Design Contradiction:
Ease of manufactureVSReliability

Solution Approach 1:

The patent changes the thermal conductivity parameter of plastic by adding metal fillers. The filled plastic achieves thermal conductivity values between 0.5-30 W/mK (preferably 2-10 W/mK), which is sufficiently high to create the cold metal sensation on touch while maintaining the cost-effectiveness and mechanical durability of plastic.

Inventive Principle:
Principle #35Parameter changes

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 filled plastic control element provides a 'cool touch' similar to metal, is resistant to mechanical stress, and allows for adjustable thermal conductivity suitable for various household appliance temperatures, offering a high-quality feel without the limitations of pure metal or thin coatings.

Implementation Method 1

the plastic is filled with a filler which has a higher thermal conductivity than the plastic

Methodology Applied
Scientific EffectThermal conduction: Conduction (thermal)

Data Source

PatentEP2697568B1Control element and a household device
Publication Date: 2016.11.30 BSH HAUSGERATE GMBH
  • EP2697568B1 patent drawingFigure 1~2

AI summary

The invention relates to an operator control element for a domestic appliance, wherein the operator control element (1) has a main body (10) which is composed of plastic. The operator control element is characterized in that the plastic is admixed with filler which has a higher thermal conductivity than the plastic. The invention also relates to a domestic appliance having at least one operator control element. The operator control element is characterized in that at least one of the operator control elements constitutes an operator control element having a main body (10) which is composed of plastic, wherein the plastic is admixed with filler which has a higher thermal conductivity than the plastic.