Variable Length Cooling Element for Explosion-Proof Light Fixture

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Solution Overview

Problem

Existing lamp designs for hazardous areas face challenges in heat transfer from the light source to the cooling device due to manufacturing tolerances, which can impair the cooling efficiency and reduce the service life and light output of LEDs, especially at high temperatures.

Innovation Solution

The use of a length-variable cooling element that can adjust its length to ensure optimal contact between the cooling device and the lamp housing, such as a cooling spring or telescoping element, to enhance heat transfer without the need for thermal paste, thereby compensating for manufacturing tolerances and improving thermal contact.

Engineering Contradictions & Design Principles

VSEngineering Contradiction Analysis

1Manufacturing precision

If a fixed-length cooling device is used, then the structure is simple, but manufacturing tolerances impair heat transfer efficiency

Engineering Contradiction:
Improveheat transfer contactVSAvoidcooling device structure
Core Design Contradiction:
Manufacturing precisionVSDevice complexity

Solution Approach 1:

The cooling device employs a spring element that can dynamically adjust its length to compensate for manufacturing tolerances and ensure optimal thermal contact between the light source, cooling device, and housing. The spring's elastic deformation allows the system to adapt to dimensional variations without requiring high-precision manufacturing.

Inventive Principle:
Principle #15Dynamics

2Manufacturing precision

If thermal paste is applied to compensate for manufacturing tolerances, then heat transfer is improved, but the device complexity and potential safety risks increase

Engineering Contradiction:
Improveheat transfer contactVSAvoidthermal interface requirements
Core Design Contradiction:
Manufacturing precisionVSDevice complexity

Solution Approach 1:

The spring element acts as a mechanical intermediary that transmits and maintains thermal contact pressure between the cooling device and housing. By using the spring's elastic properties to ensure continuous contact, the invention eliminates the need for thermal paste while maintaining effective heat transfer through direct solid-to-solid contact.

Inventive Principle:
Principle #24Intermediary (Mediator)

3Reliability

If the cooling device is made rigid to ensure stable contact, then manufacturing tolerances are critical, but adaptability to tolerance variations is reduced

Engineering Contradiction:
Improvethermal contact stabilityVSAvoidtolerance compensation
Core Design Contradiction:
ReliabilityVSAdaptability or versatility

Solution Approach 1:

The cooling device utilizes the spring's variable length parameter, which can change within elastic limits to adapt to manufacturing tolerances. The spring's force constant and deflection characteristics are selected to provide stable contact pressure while accommodating dimensional variations, achieving both reliability and adaptability through controlled parameter variation.

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

This solution effectively increases the heat transfer efficiency between the light source and the lamp housing, reducing the risk of LED damage and maintaining performance even at elevated temperatures, potentially eliminating the need for additional active cooling methods like fans.

Implementation Method 1

a first cooling element in the form of a cooling spring (10) arranged on one side of the heat sink (7), which extends between an end face of the heat sink (7) and a housing part (8)

Methodology Applied
Scientific EffectThermal conduction: Conduction (thermal)

Implementation Method 2

a first cooling element in the form of a cooling spring (10) arranged on one side of the heat sink (7), which extends between an end face of the heat sink (7) and a housing part (8)

Methodology Applied
Scientific EffectElasticity: Elasticity

Data Source

PatentEP3087311B1Light fixture
Publication Date: 2019.11.27 EATON PROTECTION SYST IP GMBH & CO
  • EP3087311B1 patent drawingFigure 1~2

AI summary

A light fixture, in particular for use in areas in which there is a risk of explosions, has at least a lighting means, a cooling device for the lighting means and a light fixture housing with a light exit opening, wherein at least the lighting means and the cooling device are arranged in the light fixture housing. In order to improve heat transfer from the lighting means, in particular from the cooling device, to the light fixture housing in a simple and reliable manner without the additional use of a thermally conductive paste or the like, wherein corresponding manufacturing tolerances, which can have a negative influence on good thermal contact, no longer have to be taken into account, the cooling device has, for heat transfer to the light fixture housing, a cooling element of variable length or is in the form of a cooling element of variable length.