Automotive LED Lamp Spring Element Thermal Stress
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Solution Overview
Problem
Automotive solid-state lamps face reliability issues due to thermal stresses and material elongations across different temperature ranges, potentially damaging wire bonding connections and affecting lamp operation.
Innovation Solution
Incorporating spring-like elements made of soft, electrically conductive materials with enhanced deformability in both the light source and support formations to absorb thermal strains, allowing for cooperative action in managing differential elongations caused by varying coefficients of thermal expansion.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Adaptability or versatility
If different materials (metal, plastics, carbon or ceramic materials) are used in the lamp, then the lamp can achieve diverse functional requirements, but the different coefficients of thermal expansion cause different elongations as temperature changes, leading to potential damage to the light source and wire bonding connections
Solution Approach 1:
The patent introduces a spring element with positive thermal expansion coefficient that expands when temperature increases, thereby compensating for the differential thermal expansion between materials with different coefficients. The spring element is connected to the light source and support formation, allowing it to absorb thermal stresses and prevent damage to wire bonding connections during temperature cycles.
2Adaptability or versatility
If the lamp structure allows movement of the light source within the housing to accommodate thermal expansion, then thermal stresses are reduced, but wire bonding connections may still be damaged due to differential elongation of materials
Solution Approach 1:
The spring element is specifically designed to compensate for thermal expansion differences. When temperature changes cause differential elongation between materials, the spring element expands or contracts accordingly, absorbing the thermal stress and protecting the wire bonding connections from damage while allowing the light source to move within the housing.
3Reliability
If spring-like elements are added to absorb thermal strains, then reliability over wide temperature ranges is improved, but device complexity increases
Solution Approach 1:
The spring element is integrated into the existing lamp structure in a minimally invasive manner. It is connected between the light source and support formation, utilizing the existing structural interfaces. This integration approach adds the necessary thermal compensation function while minimizing increases in overall device complexity.
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 reliable operation of automotive lamps over a wide temperature range (-40°C to +65°C, enhancing their durability and lifespan by mitigating damage from thermal stresses.
Implementation Method 1
spring-like element (100) having a length L, including a curvilinear portion adapted to vary its length
Implementation Method 2
different coefficients of thermal expansion. The risk therefore exists that such materials may undergo different elongations as a function of temperature
Data Source
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AI summary
A solid-state lamp (10) for vehicles comprises: a housing (12) extending in a longitudinal direction (X12) between opposed electrically conductive end caps (14), with a light-permeable portion (16) of the housing between the end caps (14), a solid-state light source (18), e.g. a LED source (182), arranged at the light-permeable portion (16) of the housing (12), electrically-conductive support formations (22) between the end caps (14) and the light source (18), the support formations (22) being configured to support the light source (18) and to provide a power supply path between the end caps (14) through the light source (18) . The lamp (10) comprises at least one spring-like element (100) having a length (L) in said longitudinal direction (X12) and being deformable to vary its length (L) in the longitudinal direction (X12) so as to be able to absorb deformation stresses caused by thermal cycles.