1. Infrared 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

2. Introduction

3. Com-Corp’s Bulb Shield
Automotive headlamp requires light shielding
Bulb shield component
Metal stamping
Decorative nickel chrome plating
New light bulbs and lamp designs were causing bulb shield to overheat

4. Bulb shield orientation
Figure 1 Cross section of a headlamp with bulb shield (2) installed in front of bulb (1) and reflector (3)

5. Bulb shield interior coating
High temperature black paint
Applied to shield interior surface to prevent unwanted reflections
With paint Without paint

6. Bulb shield temperature
Mechanical Actions
Proximity to bulb
Lack of air flow
Thermodynamic Actions
Electromagnetic radiation absorbed by the shield
Interior coating reflectivity
Exterior coating low emissivity

7. Deleterious effects of elevated temperature
Oxidation of Ni-Cr at 315° Celsius
Yellow oxide reflects in lamp
EDS graph of discolored area

8. Deleterious effects of elevated temperature
Bulb shield required to pass SAE vibration test
Tensile strength of steel reduced at elevated temperatures

9. Previous research efforts to reduce shield temperature
Sah and Park – Shape and Orientation
Geometry of the bulb shield – air flow
Geometry of the reflector
Location of shield with respect to the bulb
Reduced bulb shield temperature by 15-20%

10. Economic impact of those solutions
Alter geometry of the bulb shield
Changes to existing tooling
Mechanical integrity of the shield
Geometry of the reflector
Location of shield with respect to the bulb
Changes to one or both components

11. Paint removal as a solution
No Paint
Highly reflective nickel-Chrome surface
Affects photometry of lamp
Metallic Flake Paint
Increase in reflectivity – some preferential IR

12. Research new interior coating solution
Visible wavelengths must be absorbed
Infrared should be reflected
Bulb output
Ideal coating

13. Reflectivity profiles
Normal Paint
Designed for low reflectance for headlamp photometry
New coating
Pigmented to absorb visible radiation ( nm)
Highly reflective in near infrared

14. Comparison of coating based solutions
Headlamp used as test environment
Type K thermocouple
Computer data collection interface
Sample sets randomized

15. Statistical analysis of results
ANOVA – normal distribution
ANOVA Per Paint
Source of Variation F
P-value
F critical
Between Groups
3.43E-18

16. Performance Only un-coated shield performed better
IR reflective sample 2 was best performer

17. Comparison to metallic flake coating
Both show statistically significant reductions in temperature
IR reflective was 5.7% cooler than metallic flake

18. Shield Proximity Factor
Eliminate variation in shield geometry as variable
No statistical significance in shield proximity to bulb between sample sets
IR 2 samples were actually closest to bulb

19. Conclusion Infrared reflective bulb shield
Comparable reduction in temperature to altering lamp design
No special handling
No increase in cost
Maintain low visible reflectance
U.S. and foreign patents pending

20. Contact Information
Isatec Tooling and Engineering
Dr. Steven Sheng
Illume LLC
Michael Strazzanti