EP0095120A1 - Vehicle headlamp or the like having a layer which prevents localized heating - Google Patents

Vehicle headlamp or the like having a layer which prevents localized heating Download PDF

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Publication number
EP0095120A1
EP0095120A1 EP83104816A EP83104816A EP0095120A1 EP 0095120 A1 EP0095120 A1 EP 0095120A1 EP 83104816 A EP83104816 A EP 83104816A EP 83104816 A EP83104816 A EP 83104816A EP 0095120 A1 EP0095120 A1 EP 0095120A1
Authority
EP
European Patent Office
Prior art keywords
layer
sheet
graphite
source
heat
Prior art date
Legal status (The legal status is an assumption and is not a legal conclusion. Google has not performed a legal analysis and makes no representation as to the accuracy of the status listed.)
Withdrawn
Application number
EP83104816A
Other languages
German (de)
English (en)
French (fr)
Inventor
Kazuo Maruya
Masashi Yamabe
Current Assignee (The listed assignees may be inaccurate. Google has not performed a legal analysis and makes no representation or warranty as to the accuracy of the list.)
Nissan Motor Co Ltd
Original Assignee
Nissan Motor Co Ltd
Priority date (The priority date is an assumption and is not a legal conclusion. Google has not performed a legal analysis and makes no representation as to the accuracy of the date listed.)
Filing date
Publication date
Application filed by Nissan Motor Co Ltd filed Critical Nissan Motor Co Ltd
Publication of EP0095120A1 publication Critical patent/EP0095120A1/en
Withdrawn legal-status Critical Current

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Classifications

    • F—MECHANICAL ENGINEERING; LIGHTING; HEATING; WEAPONS; BLASTING
    • F21—LIGHTING
    • F21S—NON-PORTABLE LIGHTING DEVICES; SYSTEMS THEREOF; VEHICLE LIGHTING DEVICES SPECIALLY ADAPTED FOR VEHICLE EXTERIORS
    • F21S41/00—Illuminating devices specially adapted for vehicle exteriors, e.g. headlamps
    • F21S41/30—Illuminating devices specially adapted for vehicle exteriors, e.g. headlamps characterised by reflectors
    • F21S41/37—Illuminating devices specially adapted for vehicle exteriors, e.g. headlamps characterised by reflectors characterised by their material, surface treatment or coatings
    • F—MECHANICAL ENGINEERING; LIGHTING; HEATING; WEAPONS; BLASTING
    • F21—LIGHTING
    • F21S—NON-PORTABLE LIGHTING DEVICES; SYSTEMS THEREOF; VEHICLE LIGHTING DEVICES SPECIALLY ADAPTED FOR VEHICLE EXTERIORS
    • F21S45/00—Arrangements within vehicle lighting devices specially adapted for vehicle exteriors, for purposes other than emission or distribution of light
    • F21S45/10—Protection of lighting devices
    • F—MECHANICAL ENGINEERING; LIGHTING; HEATING; WEAPONS; BLASTING
    • F21—LIGHTING
    • F21S—NON-PORTABLE LIGHTING DEVICES; SYSTEMS THEREOF; VEHICLE LIGHTING DEVICES SPECIALLY ADAPTED FOR VEHICLE EXTERIORS
    • F21S45/00—Arrangements within vehicle lighting devices specially adapted for vehicle exteriors, for purposes other than emission or distribution of light
    • F21S45/40—Cooling of lighting devices
    • F—MECHANICAL ENGINEERING; LIGHTING; HEATING; WEAPONS; BLASTING
    • F21—LIGHTING
    • F21V—FUNCTIONAL FEATURES OR DETAILS OF LIGHTING DEVICES OR SYSTEMS THEREOF; STRUCTURAL COMBINATIONS OF LIGHTING DEVICES WITH OTHER ARTICLES, NOT OTHERWISE PROVIDED FOR
    • F21V7/00—Reflectors for light sources
    • F21V7/22—Reflectors for light sources characterised by materials, surface treatments or coatings, e.g. dichroic reflectors
    • F21V7/24—Reflectors for light sources characterised by materials, surface treatments or coatings, e.g. dichroic reflectors characterised by the material
    • F—MECHANICAL ENGINEERING; LIGHTING; HEATING; WEAPONS; BLASTING
    • F21—LIGHTING
    • F21V—FUNCTIONAL FEATURES OR DETAILS OF LIGHTING DEVICES OR SYSTEMS THEREOF; STRUCTURAL COMBINATIONS OF LIGHTING DEVICES WITH OTHER ARTICLES, NOT OTHERWISE PROVIDED FOR
    • F21V7/00—Reflectors for light sources
    • F21V7/22—Reflectors for light sources characterised by materials, surface treatments or coatings, e.g. dichroic reflectors
    • F21V7/28—Reflectors for light sources characterised by materials, surface treatments or coatings, e.g. dichroic reflectors characterised by coatings

Definitions

  • the present invention relates generally to a device having a housing exposed to a source of heat and which is subject to localized heating and more specifically to a device such as a vehicle headlamp in which a layer of material is provide to disperse the heat produced by the light source and prevent localized thermal damage.
  • a vehicle headlamp 1 has been formed of plastic to overcome the production difficulties involved with deep drawing metal sheet, and provided with a base coat, metallic reflective coat and top or finishing coat (which coats are shown as a single relatively thick coat 2 for the sake of illustration only).
  • This arrangement while solving the problems inherent with deep drawing metal sheet, has encountered the problem that when low beam (produced by filament 3) is continuously used for prolonged periods, localized heating of the reflector housing 4 occurs above and slightly forward of the bulb 5.
  • low beam produced by filament 3
  • the temperatures at points A B C D and E were determined. The results are set forth in Table 1. shown below.
  • the zone in close proximity of point A develops a very high temperature and tends to be thermally deformed, expanded or decomposed to the point of reducing the light reflection efficiency of the device.
  • a plastic having a high thermal resistance e.g. a plastic which can withstand temperatures in excess of 200 degrees C.
  • a heat shield 5 such as shown in Fig. 3.
  • This heat shield 5 can be made of a light metal such as aluminimum but must be disposed at a suitable distance from the actual surface of the reflector housing to prevent heat being conducted directly thereto. Accordingly, an arrangement such as illustrated has been proposed wherein the heat shield 5 is received in slotted extensions 6 which depend from the upper surface 7 of the housing 8.
  • the present invention in a broad sense takes the form of a device comprising a member exposed to a source of heat and a layer of material disposed on a surface of said housing in proximity of the heat source, the sheet conducting heat along its surface faster than through its thickness in a manner that localized heating of the housing is prevented.
  • the present invention features a sheet of flexible graphite (a material which exibits anisotropic heat conduction prpperites) which is disposed on the concave surface of a moulded plastic headlamp reflector or the like (having a limited thermal resistance), above a source of heat such as light bulb or similar light source.
  • the sheet conducts heat along the surface thereof faster than through the thickness thereof so that localized heating of the reflector in proximity of the source is prevented.
  • a layer or sheet of flexible graphite 10 is disposed on the concave surface 12 of the reflector housing above the light bulb 14. As shown, the graphite layer 10 terminates just before the attachment flange 16 of the housing upon which the lens or transparent cover (not shown) of the arrangement is attached.
  • the basic body 18 of the housing is formed by injection moulding (or the like) a synthetic thermoplastic resin such as 6-nylon, 6-6 nylon, denatured polyphenylene oxide, polycarbonate, polyethylene terephthalate or one of the just mentioned resins reinforced with inorganic materials (e.g. glass fiber).
  • Thermosetting resins such as phenolic and polyester resins may also be used.
  • Materials such as polyethylene and polypropylene for example, are generally less desirable because of lower mechanical strength and heat resistance and poor painting and adhesion characteristics.
  • the basic body 18 of the device according to the embodiment shown in Fig. 4 is provided with a base coat or film to seal the surface of the body and prevent the formation of gas during the vacuum evaporation depositing of the reflective metallic second coat.
  • a third top or finishing coat is applied to the reflective surface to finish the article.
  • the anisotropic heat conductive layer which characterizes the present invention in the disclosed embodiment is formed by grinding natural graphite, kish, thermally decomposed graphite or the like, having a highly layered crystalline structure, treating the resulting powder in a powerful oxiding medium such as concentrated sulphuric acid/ permanganate solution and subsequently heating the resulting product to about 800 to 1000 degrees C. whereby suphur oxide gases (SO x ) are generated which expand the particles to 10 to 200 times their original size.
  • SO x suphur oxide gases
  • NICA film produced by the NIPPON CARBON CO. LTD.
  • GRATFOIL produced by the UNION CARBIDE CORP.
  • BALCAFOIL produced by the NIPPON BALCA CO. LTD.
  • a sheet of flexible graphite of the nature described above contains no organic matter and therefore exhibits good stability at elevated temperatures in air and further exhibits a heat conduction anistropy wherein heat is conducted along the suface of the sheet faster then though the thickness thereof.
  • a flexible graphite sheet having a density within a range of 0.7 - 1.9gm/cm 3 and a thickness within the range of 0.05 - 1.0mm it has been found that a sheet having a density lower than 0.7 gm/cm 3 lacks tensile strength and that a sheet having a density above 1.ggm/cm 3 is difficult and expensive to produce. Further, a sheet having a thickness of less than 0.05mm lacks mechanical strength and is readily damaged during production while a sheet having a thickness in excess of 1.0mm is difficult and expensive to produce.
  • the graphite sheet so as to have a contour which corresponds to that part of the base body on which it is to be disposed.
  • This two methods are possible.
  • One is to compress the expanded graphite particles using a mould having a shape which corresponds in contour to that of the site which which the sheet is to be attached.
  • the second is to first form the sheet by calender rolling and then place the thus formed sheet in the same mould.
  • a sheet having a density of 0.2 - 0.5gm/cm 3 which is pressed using a rubber pressing method (preferably using hydraulic pressure) has been found suitable.
  • the graphite sheet may be disposed directly on the basic body and bonded in position using an adhesive having good heat and adhesive properties with respect to both of the base body material and the graphite sheet.
  • adhesives of the epoxy or phenol group have been found suitable.
  • PLYOPHEN TD-735 phenolic type
  • PLYOPHEN LA-1159 epoxy type
  • the base coat may be first applied to the base body and the graphite sheet set into the paint film while it is still fluid after which the surface of the graphite sheet may be coated.
  • the base coat is provided not only to provide a smooth surface on which to apply the reflective layer but to suppress generation of gas upon exposure to a vacuum.
  • the base coat may take the form of a conventional urethane, polyester or melamine- alkyd type paint.
  • the selection of the paint of course must be made taking into account its heat resistance and adhesion to both of the base body and the graphite sheet.
  • the paint may be applied using a flow-coater if desired and in a manner to provide a thickness of 10 - 20 .
  • the reflective film may be applied using a vapour deposition technique.
  • a vapour deposition technique Either of a resistor heating vapour depositing technique or a sputtering deposition techique may be used.
  • the resistor heating method is deemed advantageous, however in the case that the metal to be applied is chromium or stainless steel the sputtering technique is preferred.
  • the thickness of this layer should be from 500 - 3000 ⁇ .
  • the final or top coat which may be a urethane or acryl melamine varnish, by way of example, should be formed on top of the reflective layer in a manner to have a thickness of 5 to 15 u .
  • each base body was washed with acetone and subsequently spray painted with EXP1436A, EXP1436B and EXP1436C (manufactured by the FUJIKURA KASEI CO. LTD.) mixed in the weight ratio of 100:20:25, in a manner to form a paint layer having a thickness of approximately 20 u .
  • the base bodies were then fired for 1Hr. at 170 degrees C.
  • an aluminium reflective film having a thickness of approximately 700 A was vacuum deposited on each using a resistor evaporation technique.
  • the top coat consisting of EXP 1434 (a single component type urethane varnish) and SL8395 thinner (FUJIKURA KASEI CO.
  • a top coat of AL-3 an acryl melamine type varnish produced by NIPPON OIL AND FATS CO., LTD.
  • SL8395 thinner FUJIKURA KASEI CO., LTD.
  • the present invention is not limited to headlight reflectors and may find application in other devices and apparatus wherein localized heating is a problem.

Landscapes

  • Engineering & Computer Science (AREA)
  • General Engineering & Computer Science (AREA)
  • Non-Portable Lighting Devices Or Systems Thereof (AREA)
  • Optical Elements Other Than Lenses (AREA)
  • Arrangement Of Elements, Cooling, Sealing, Or The Like Of Lighting Devices (AREA)
EP83104816A 1982-05-21 1983-05-16 Vehicle headlamp or the like having a layer which prevents localized heating Withdrawn EP0095120A1 (en)

Applications Claiming Priority (2)

Application Number Priority Date Filing Date Title
JP57086352A JPS58203402A (ja) 1982-05-21 1982-05-21 ランプ用樹脂製リフレクタ−
JP86352/82 1982-05-21

Publications (1)

Publication Number Publication Date
EP0095120A1 true EP0095120A1 (en) 1983-11-30

Family

ID=13884483

Family Applications (1)

Application Number Title Priority Date Filing Date
EP83104816A Withdrawn EP0095120A1 (en) 1982-05-21 1983-05-16 Vehicle headlamp or the like having a layer which prevents localized heating

Country Status (2)

Country Link
EP (1) EP0095120A1 (ja)
JP (1) JPS58203402A (ja)

Cited By (3)

* Cited by examiner, † Cited by third party
Publication number Priority date Publication date Assignee Title
FR2636408A1 (fr) * 1988-09-12 1990-03-16 Valeo Projecteur d'eclairage a reflecteur en matiere plastique de section droite rectangulaire et muni d'un ecran thermique
WO2009003608A1 (en) * 2007-06-29 2009-01-08 Dsm Ip Assets B.V. Improved mirror optic sytem
FR3104682A1 (fr) * 2019-12-11 2021-06-18 Valeo Vision Dispositif lumineux utilisant un matériau orthotrope

Families Citing this family (3)

* Cited by examiner, † Cited by third party
Publication number Priority date Publication date Assignee Title
JPH0610562Y2 (ja) * 1987-09-04 1994-03-16 日産自動車株式会社 プロジェクタ型ヘッドランプ
ATE549735T1 (de) * 2001-08-31 2012-03-15 Cool Options Inc Thermisch leitfähiger lampenreflektor
JP4716421B2 (ja) * 2006-01-17 2011-07-06 株式会社小糸製作所 合成樹脂製灯具構成部材の表面被膜形成方法および合成樹脂製灯具構成部材

Citations (3)

* Cited by examiner, † Cited by third party
Publication number Priority date Publication date Assignee Title
FR467938A (fr) * 1914-01-31 1914-06-24 Compagnie Francaise De Charbons Pour L Electricite Réflecteur en charbon
GB2017127A (en) * 1978-03-20 1979-10-03 Sev Marchal Reflector
FR2447794A1 (fr) * 1979-02-05 1980-08-29 Valentine Cie Vernis Procede de revetement de matieres plastiques thermodurcissables et produits obtenus selon ce procede

Family Cites Families (2)

* Cited by examiner, † Cited by third party
Publication number Priority date Publication date Assignee Title
JPS5212544B2 (ja) * 1973-07-30 1977-04-07
JPS5726751Y2 (ja) * 1975-07-15 1982-06-10

Patent Citations (3)

* Cited by examiner, † Cited by third party
Publication number Priority date Publication date Assignee Title
FR467938A (fr) * 1914-01-31 1914-06-24 Compagnie Francaise De Charbons Pour L Electricite Réflecteur en charbon
GB2017127A (en) * 1978-03-20 1979-10-03 Sev Marchal Reflector
FR2447794A1 (fr) * 1979-02-05 1980-08-29 Valentine Cie Vernis Procede de revetement de matieres plastiques thermodurcissables et produits obtenus selon ce procede

Cited By (4)

* Cited by examiner, † Cited by third party
Publication number Priority date Publication date Assignee Title
FR2636408A1 (fr) * 1988-09-12 1990-03-16 Valeo Projecteur d'eclairage a reflecteur en matiere plastique de section droite rectangulaire et muni d'un ecran thermique
WO2009003608A1 (en) * 2007-06-29 2009-01-08 Dsm Ip Assets B.V. Improved mirror optic sytem
CN101688027B (zh) * 2007-06-29 2013-05-22 帝斯曼知识产权资产管理有限公司 改进的反射镜光学系统
FR3104682A1 (fr) * 2019-12-11 2021-06-18 Valeo Vision Dispositif lumineux utilisant un matériau orthotrope

Also Published As

Publication number Publication date
JPS58203402A (ja) 1983-11-26
JPH0115041B2 (ja) 1989-03-15

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Date Code Title Description
PUAI Public reference made under article 153(3) epc to a published international application that has entered the european phase

Free format text: ORIGINAL CODE: 0009012

17P Request for examination filed

Effective date: 19830516

AK Designated contracting states

Designated state(s): DE FR GB

RAP1 Party data changed (applicant data changed or rights of an application transferred)

Owner name: NISSAN MOTOR CO., LTD.

STAA Information on the status of an ep patent application or granted ep patent

Free format text: STATUS: THE APPLICATION HAS BEEN WITHDRAWN

18W Application withdrawn

Withdrawal date: 19850723

RIN1 Information on inventor provided before grant (corrected)

Inventor name: YAMABE, MASASHI

Inventor name: MARUYA, KAZUO