Infrared Reflective Bulb ShieldInfrared Reflective Bulb Shield

Com-Corp Industries•Tier 1-2 automotive metal stamping and manufacturing

Isatec Technical Center•Captive tooling, engineering and process design

Illume•Affiliated advanced research and development company

IntroductionIntroduction

Illume researches

solution

Isatec designs

manufacturing process

Com-Corp has a

problem

Com-Corp’s Bulb ShieldCom-Corp’s Bulb Shield

Automotive headlamp requires light shieldingAutomotive headlamp requires light shielding Bulb shield component Bulb shield component

• Metal stampingMetal stamping• Decorative nickel chrome platingDecorative nickel chrome plating• New light bulbs and lamp designs were causing bulb New light bulbs and lamp designs were causing bulb

shield to overheatshield to overheat

Bulb shield orientationBulb shield orientation

Figure 1 Cross section of a headlamp with bulb shield (2) installed in front of bulb (1) and reflector

(3)

Bulb shield interior coatingBulb shield interior coating

High temperature black paintHigh temperature black paint

• Applied to shield interior surface to prevent Applied to shield interior surface to prevent unwanted reflectionsunwanted reflections

With paint Without paint

Bulb shield temperatureBulb shield temperature

Mechanical ActionsMechanical Actions

• Proximity to bulbProximity to bulb

• Lack of air flowLack of air flow

Thermodynamic ActionsThermodynamic Actions

• Electromagnetic radiation absorbed by the Electromagnetic radiation absorbed by the shieldshield

Interior coating reflectivityInterior coating reflectivity

Exterior coating low emissivityExterior coating low emissivity

Deleterious effects of elevated Deleterious effects of elevated temperaturetemperature

Oxidation of Ni-Cr at Oxidation of Ni-Cr at 315315° Celsius° Celsius• Yellow oxide Yellow oxide

reflects in lampreflects in lamp

EDS graph of discolored area

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Deleterious effects of elevated Deleterious effects of elevated temperaturetemperature

• Bulb shield Bulb shield required to required to pass SAE pass SAE vibration testvibration test

• Tensile strength Tensile strength of steel reduced of steel reduced at elevated at elevated temperaturestemperatures

Previous research efforts to reduce Previous research efforts to reduce shield temperatureshield temperature

Sah and Park – Shape and Sah and Park – Shape and OrientationOrientation

• Geometry of the bulb shield – air flowGeometry of the bulb shield – air flow

• Geometry of the reflectorGeometry of the reflector

• Location of shield with respect to the bulbLocation of shield with respect to the bulb

• Reduced bulb shield temperature by 15-20%Reduced bulb shield temperature by 15-20%

Economic impact of those solutionsEconomic impact of those solutions

• Alter geometry of the bulb shieldAlter geometry of the bulb shield Changes to existing toolingChanges to existing tooling Mechanical integrity of the shieldMechanical integrity of the shield

• Geometry of the reflectorGeometry of the reflector Changes to existing toolingChanges to existing tooling

• Location of shield with respect to the bulbLocation of shield with respect to the bulb Changes to one or both componentsChanges to one or both components

Paint removal as a solutionPaint removal as a solution

No PaintNo Paint• Highly reflective Highly reflective

nickel-Chrome nickel-Chrome surfacesurface

• Affects photometry Affects photometry of lampof lamp

Metallic Flake PaintMetallic Flake Paint• Increase in Increase in

reflectivity – some reflectivity – some preferential IRpreferential IR

Research new interior coating Research new interior coating solution solution

• Visible wavelengths Visible wavelengths must be absorbedmust be absorbed

• Infrared should be Infrared should be reflectedreflected

Bulb output

Ideal coating

Reflectivity profilesReflectivity profiles

Normal PaintNormal Paint• Designed for low Designed for low

reflectance for headlamp reflectance for headlamp photometryphotometry

New coatingNew coating• Pigmented to absorb visible Pigmented to absorb visible

radiation (490-720nm)radiation (490-720nm)• Highly reflective in near infraredHighly reflective in near infrared

Comparison of coating based Comparison of coating based solutions solutions

Headlamp used as Headlamp used as test environmenttest environment

Type K thermocoupleType K thermocouple

Computer data Computer data collectioncollection interfaceinterface

Sample sets Sample sets randomizedrandomized

Statistical analysis of resultsStatistical analysis of results

ANOVA – normal ANOVA – normal distributiondistribution

ANOVA Per PaintANOVA Per Paint

Source of VariationSource of Variation FF P-valueP-value F criticalF critical

Between GroupsBetween Groups 24.1959244324.19592443 3.43E-183.43E-18 2.0166012.016601

PerformancePerformance

Only un-coated Only un-coated shield performed shield performed betterbetter

IR reflective IR reflective sample 2 was best sample 2 was best performerperformer

Comparison to metallic flake Comparison to metallic flake coatingcoating

ANOVATemperature per sub group

Groups Count Sum Average VarianceIR 2 3 694.18 231.393 23.64213Silver Black 3 736.34 245.447 55.28903Std. Black 3 874.28 291.427 1.040433

ANOVASource of Variation F P-value F critBetween Groups 111 1.824E-05 5.14325

Both show Both show statistically statistically significant significant reductions in reductions in temperaturetemperature

IR reflective was IR reflective was 5.7% cooler than 5.7% cooler than metallic flakemetallic flake

Shield Proximity FactorShield Proximity Factor

Eliminate variation in shield geometry as variableEliminate variation in shield geometry as variable

• No statistical significance in shield proximity to bulb between No statistical significance in shield proximity to bulb between sample setssample sets

• IR 2 samples were actually closest to bulbIR 2 samples were actually closest to bulb

ConclusionConclusion

Infrared reflective bulb shieldInfrared reflective bulb shield

• Comparable reduction in temperature to Comparable reduction in temperature to altering lamp designaltering lamp design

• No special handlingNo special handling• No increase in costNo increase in cost• Maintain low visible reflectanceMaintain low visible reflectance• U.S. and foreign patents pendingU.S. and foreign patents pending

Contact InformationContact Information

Isatec Tooling and EngineeringIsatec Tooling and EngineeringDr. Steven ShengDr. Steven Shengssheng@ccioh.comssheng@ccioh.com216-265-9449216-265-9449

Illume LLCIllume LLCMichael StrazzantiMichael Strazzantimstrazz@illumeco.commstrazz@illumeco.com216-299-3567216-299-3567