Variable Thermal Resistance Heat Sink for Motor Vehicle Headlights

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Solution Overview

Problem

Motor vehicle headlights face challenges in cooling light sources due to high temperatures in the engine compartment, which can lead to overheating and reduced performance, especially for light-emitting diodes, as conventional heat sink devices either fail to dissipate heat effectively or risk heating up the interior further.

Innovation Solution

A heat sink device with two separated elements and a contacting mechanism that allows heat exchange only when the interior temperature exceeds the external temperature, using bimetal control elements to manage contact and prevent heat transfer when the interior is cooler, ensuring efficient cooling without overheating.

Engineering Contradictions & Design Principles

VSEngineering Contradiction Analysis

1Temperature

If a heat sink device is arranged in the direction of the engine compartment to dissipate heat, then heat dissipation is improved, but the light sources are exposed to high temperatures from the engine compartment

Engineering Contradiction:
Improveheat dissipationVSAvoidhigh temperature exposure
Core Design Contradiction:
TemperatureVSObject-affected harmful factors

Solution Approach 1:

The heat sink is divided into two separate elements: a first heat sink element positioned in the headlight interior near the light sources, and a second heat sink element positioned in the engine compartment direction. These elements are separated by an air gap, allowing independent positioning and function optimization for both heat absorption and heat dissipation.

Inventive Principle:
Principle #1Segmentation

Solution Approach 2:

A contacting device with contact elements acts as an intermediary between the two heat sink elements. This contacting device enables conditional thermal connection - it allows heat transfer when the headlight interior temperature exceeds the engine compartment temperature, but prevents heat transfer when the engine compartment temperature is higher, thus protecting the light sources.

Inventive Principle:
Principle #24Intermediary (Mediator)

2Productivity

If the heat sink elements are continuously connected for heat exchange, then heat dissipation efficiency is improved, but heat is transferred to the light sources when engine compartment temperature is higher

Engineering Contradiction:
Improveheat dissipation efficiencyVSAvoidtemperature protection
Core Design Contradiction:
ProductivityVSReliability

Solution Approach 1:

The contacting device is designed with movable contact elements that can dynamically adjust their position based on temperature conditions. The contact elements are displaceable along the heat sink elements, enabling the system to transition between connected and disconnected states. This dynamic adjustment allows the system to optimize heat dissipation when needed while protecting light sources when engine compartment temperatures are high.

Inventive Principle:
Principle #15Dynamics

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

Effectively shields light sources from high engine compartment temperatures, maintaining optimal operating conditions for the light sources by ensuring heat is dissipated only when necessary, thereby enhancing performance and longevity.

Implementation Method 1

the first heat sink element is placed in heat transfer contact with the at least one light source arranged in the headlight housing

Methodology Applied
Scientific EffectThermal conduction: Conduction (thermal)

Implementation Method 2

a second heat sink element is mounted outside the motor vehicle headlight

Methodology Applied
Scientific EffectThermal radiation: Thermal Radiation

Implementation Method 3

the heat sink device being provided with a contacting device, which is designed in such a way that heat exchange between the heat sink elements takes place via this contacting device

Methodology Applied
Scientific EffectConvection: Convection

Implementation Method 4

the contacting device comprises one or more contact elements, which enables heat exchange between the heat sink elements when the temperature in the interior of the motor vehicle headlight is higher than the temperature in the area outside the motor vehicle headlight

Methodology Applied
Scientific EffectThermal conduction: Conduction (thermal)

Implementation Method 5

using bimetal control elements to manage contact and prevent heat transfer when the interior is cooler

Methodology Applied
Scientific EffectThermal expansion: Thermal Expansion

Data Source

PatentEP3542098B1Heat sink having variable thermal resistance
Publication Date: 2021.12.15 ZKW GRP GMBH
  • EP3542098B1 patent drawingFigure 1~2
  • EP3542098B1 patent drawingFigure 3~4
  • EP3542098B1 patent drawingFigure 5~10

AI summary

The invention relates to a motor vehicle headlight (100), comprising a headlight housing (102) and a cover plate (103) having at least one light source (104, 105) arranged in said motor vehicle headlight (100). In order to cool the at least one light source (104, 105), a heat sink device (200) is provided. Said heat sink device (200) comprises two heat sink elements (106, 107, 201, 202, 501, 502, 601, 602, 701, 702, 801, 802, 901, 902, 1001, 1002) that are separated from one another by an air gap (209) and that are arranged in such a way that a first heat sink element (106, 201, 501, 601, 701, 801, 901, 1001) is mounted inside the motor vehicle headlight (100), and a second heat sink element (107, 202, 502, 602, 702, 802, 902, 1002) is mounted outside the motor vehicle headlight (100). The heat sink device (200) is provided with a contacting device (210) that allows a heat exchange between the heat sink elements (106, 107, 201, 202, 501, 502, 601, 602, 701, 702, 801, 802, 901, 902, 1001, 1002) via said contacting device (210), whenever the temperature inside the motor vehicle headlight (100) is higher than the temperature in the area outside the motor vehicle headlight (100), and no heat exchange between the heat sink elements (106, 107, 201, 202, 501, 502, 601, 602, 701, 702, 801, 802, 901, 902, 1001, 1002) is possible whenever the temperature inside the motor vehicle headlight (100) is lower than the temperature in the area outside the motor vehicle headlight (100).