WO2012080917A2 - A luminaire - Google Patents

A luminaire Download PDF

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Publication number
WO2012080917A2
WO2012080917A2 PCT/IB2011/055553 IB2011055553W WO2012080917A2 WO 2012080917 A2 WO2012080917 A2 WO 2012080917A2 IB 2011055553 W IB2011055553 W IB 2011055553W WO 2012080917 A2 WO2012080917 A2 WO 2012080917A2
Authority
WO
WIPO (PCT)
Prior art keywords
sunshade
luminaire
light emitting
emitting element
thermal diode
Prior art date
Application number
PCT/IB2011/055553
Other languages
French (fr)
Other versions
WO2012080917A3 (en
Inventor
Joris Jan Vrehen
Mark Verhoeven
Omke Jan Teerling
Cristina Tanase
Original Assignee
Koninklijke Philips Electronics N.V.
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 Koninklijke Philips Electronics N.V. filed Critical Koninklijke Philips Electronics N.V.
Publication of WO2012080917A2 publication Critical patent/WO2012080917A2/en
Publication of WO2012080917A3 publication Critical patent/WO2012080917A3/en

Links

Classifications

    • 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
    • F21V29/00—Protecting lighting devices from thermal damage; Cooling or heating arrangements specially adapted for lighting devices or systems
    • F21V29/50—Cooling arrangements
    • F21V29/51—Cooling arrangements using condensation or evaporation of a fluid, e.g. heat pipes
    • 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
    • F21V29/00—Protecting lighting devices from thermal damage; Cooling or heating arrangements specially adapted for lighting devices or systems
    • F—MECHANICAL ENGINEERING; LIGHTING; HEATING; WEAPONS; BLASTING
    • F21—LIGHTING
    • F21S—NON-PORTABLE LIGHTING DEVICES; SYSTEMS THEREOF; VEHICLE LIGHTING DEVICES SPECIALLY ADAPTED FOR VEHICLE EXTERIORS
    • F21S8/00—Lighting devices intended for fixed installation
    • F21S8/08—Lighting devices intended for fixed installation with a standard
    • F—MECHANICAL ENGINEERING; LIGHTING; HEATING; WEAPONS; BLASTING
    • F21—LIGHTING
    • F21Y—INDEXING SCHEME ASSOCIATED WITH SUBCLASSES F21K, F21L, F21S and F21V, RELATING TO THE FORM OR THE KIND OF THE LIGHT SOURCES OR OF THE COLOUR OF THE LIGHT EMITTED
    • F21Y2115/00—Light-generating elements of semiconductor light sources
    • F21Y2115/10—Light-emitting diodes [LED]
    • F—MECHANICAL ENGINEERING; LIGHTING; HEATING; WEAPONS; BLASTING
    • F24—HEATING; RANGES; VENTILATING
    • F24S—SOLAR HEAT COLLECTORS; SOLAR HEAT SYSTEMS
    • F24S10/00—Solar heat collectors using working fluids
    • F24S10/90—Solar heat collectors using working fluids using internal thermosiphonic circulation
    • F24S10/95—Solar heat collectors using working fluids using internal thermosiphonic circulation having evaporator sections and condenser sections, e.g. heat pipes

Definitions

  • the invention relates to a luminaire comprising at least a light emitting element and a sunshade.
  • Such a luminaire which is known from GB2464518A, comprises an upper casing, a cover body having light transmittance, a holding chamber formed by pairing of the cover body and the upper casing and a light-emitting diode lamp set retained in the holding chamber.
  • a sunshade Atop of the outer surface of the upper casing a sunshade is located, which sunshade comprises a plate and a plurality of fixing members. The fixing members are connected between the plate and the upper casing, thereby providing a spacing distance between the plate and the upper casing.
  • Such a luminaire is being used outdoors, for example as street lighting.
  • the sunshade shields the light-emitting diode lamp set from the sun and reduces the ambient temperature thereof.
  • the spacing distance between the plate of the sunshade and the upper casing creates a space for forming a transverse convection current of cold and hot air for heat dissipation of the heat emitted by the light-emitting diode lamp set when used at night.
  • a drawback of this known luminaire is that the heat dissipation on top of the upper casing is based only on a flow of air, due to which the heat dissipation is limited.
  • the required spacing distance has a big impact on the freedom of design.
  • the luminaire comprises at least one thermal diode being thermally connected with a first end to the light emitting element and with a second end to the sunshade, wherein the second end is located higher than the first end.
  • a thermal diode is a device which has a high resistance to heat flow in one direction across it, and a low resistance for the reverse direction of heat flow.
  • the thermal diode of the luminaire according to the invention is positioned so that it has a high resistance to heat flow from the sunshade to the light emitting element and a low resistance for the reverse direction of heat flow from the light emitting element to the sunshade.
  • the sunshade prevents that sunlight reaches the light emitting element and that the light emitting element is exposed to excessive heat. Also other elements of the luminaire, like electronic power supplies and plastic lenses, can be shielded by the sunshade against direct sunlight. During daylight, no heat is transferred by the thermal diode from the second end to the first end at the light emitting element.
  • the temperature of the light emitting element will get higher than the temperature on a side of the sunshade remote from the light emitting element. Now, the thermal diode will transfer heat from the first end to the second end at the sunshade.
  • the sunshade is made of a material, like aluminium or copper, which easily transfers heat over the whole surface of the sunshade so that heat from the thermal diode will be conducted over the whole sunshade.
  • the thermal diode comprises a vapour chamber partly filled with a liquid.
  • the luminaire comprises an insulation layer located between the light emitting element and the sunshade, wherein the thermal diode extends through the insulation layer from the light emitting element to the sunshade. Due to the insulation layer, heat will be prevented from moving from the sunshade to the light emitting element and vice versa, so that heat can only be transferred in a controlled manner from the light emitting element to the sunshade by the thermal diode.
  • Fig. 1 is cross section of a first embodiment of the luminaire according to the invention
  • Figs. 2A and 2B are enlarged views of the thermal diode of the luminaire as shown in figure 1 ,
  • Fig. 3 is cross section of a second embodiment of the luminaire according to the invention.
  • FIG. 1 shows a first embodiment of a luminaire 1 according to the invention, which luminaire 1 is used as street lighting.
  • the luminaire 1 comprises a pole 2, a housing 3 connected to the pole 2 and a sunshade 6 located above the housing 3.
  • a light emitting element 4, electronic power supplies 5 and plastic lenses are located in the housing 3.
  • the light emitting element 4 comprises preferably light emitting diodes.
  • the sunshade 6 comprises a plate of thermally conductive material like aluminum, copper.
  • a layer 7 of thermal insulation material like, mineral wool, polystyrene or other lightweight insulation material is located between the housing 3 and the sunshade 6 .
  • the insulation layer 7 can be located against either the housing 3 or the sunshade 6 or against the housing 3 as well as the sunshade 6.
  • the luminaire 1 also comprises a number of thermal diodes 8, extending through the insulation layer 7 and being thermally connected with a first end 9 via or through the housing 3 to the light emitting element 4 and with a second end 10 to the sunshade 6.
  • the second end 10 is located higher than the first end 9.
  • Each thermal diode 8 comprises a vapour chamber 11 partly filled with a liquid 12 (see figure 2), for example in between 10% and 40% of the volume of the chamber is filled with liquid. If the filling is less than 10%, the amount of liquid tends to be too little to be effective in cooling for long periods. If the filling is over 40%, the space for evaporation of the liquid tends to become too small involving the risk of a build-up of relatively high vapor pressure inside the chamber and possibly requiring additional safety measures, for example to provide the chamber with a safety valve.
  • the light emitting element 4 will emit light (arrows P3) and will get hot, and the heat will be transferred via the housing 3 in the direction of arrow P4 to the first ends 9 of the thermal diodes 8. Due to the heat, the liquid 10 in the vapour chamber 11 will evaporate in the direction of arrow P5 and condensate against the second end 10 which is cooler than the first end 9, whereby heat is transferred via the second end 10 in the direction of arrow P6 to the sunshade 6.
  • the vapour chamber 11 can have a cylindrical shape from about 10 millimeter in diameter up to a rectangular shape with the size of the luminaire. A cylindrical shape with a diameter of 10-40 millimeter is preferred.
  • the liquid can be water, alcohol or refrigerant liquids as used in cooling installations.
  • FIG 3 shows a second embodiment of a luminaire 21 according to the invention, which luminaire 21 is used as street lighting.
  • the luminaire 21 differs from the luminaire 1 in that it comprises a different kind of thermal diode 28 having a second end 30 the size of which is nearly as large as the sunshade 6.
  • the thermal diode 28 comprises a number of smaller first ends 29 extending through an insulation layer 27 and being located against the light emitting element 4.
  • the insulation layer 27 is located against a wall 31 of the thermal diode 28, which wall 31 is located at a level between the first ends 29 and the second end 30.

Landscapes

  • Engineering & Computer Science (AREA)
  • General Engineering & Computer Science (AREA)
  • Arrangement Of Elements, Cooling, Sealing, Or The Like Of Lighting Devices (AREA)
  • Non-Portable Lighting Devices Or Systems Thereof (AREA)

Abstract

A luminaire (1, 21) comprises at least a light emitting element (4), a sunshade (6) and a thermal diode (8, 28) being thermally connected with a first end (9, 29) to the light emitting element (4) and with a second end (10, 30) to the sunshade (6), The second end (10, 30) is located higher than the first end (9, 29). The thermal diode (8, 28) comprises a vapour chamber (11) partly filled with a liquid (12).

Description

A luminaire
FIELD OF THE INVENTION
The invention relates to a luminaire comprising at least a light emitting element and a sunshade. BACKGROUND OF THE INVENTION
Such a luminaire, which is known from GB2464518A, comprises an upper casing, a cover body having light transmittance, a holding chamber formed by pairing of the cover body and the upper casing and a light-emitting diode lamp set retained in the holding chamber. Atop of the outer surface of the upper casing a sunshade is located, which sunshade comprises a plate and a plurality of fixing members. The fixing members are connected between the plate and the upper casing, thereby providing a spacing distance between the plate and the upper casing.
Such a luminaire is being used outdoors, for example as street lighting. During daylight when the light-emitting diode lamp set is not being used, the sunshade shields the light-emitting diode lamp set from the sun and reduces the ambient temperature thereof.
The spacing distance between the plate of the sunshade and the upper casing creates a space for forming a transverse convection current of cold and hot air for heat dissipation of the heat emitted by the light-emitting diode lamp set when used at night.
A drawback of this known luminaire is that the heat dissipation on top of the upper casing is based only on a flow of air, due to which the heat dissipation is limited.
Furthermore, the required spacing distance has a big impact on the freedom of design.
SUMMARY OF THE INVENTION
It is an object of the invention to provide a luminaire, wherein during daylight heat transfer towards the light emitting element is efficiently blocked, whilst during the night when the light emitting element is being used, improved cooling of the light emitting element is obtained.
This object is accomplished with the luminaire according to the invention in that the luminaire comprises at least one thermal diode being thermally connected with a first end to the light emitting element and with a second end to the sunshade, wherein the second end is located higher than the first end.
A thermal diode is a device which has a high resistance to heat flow in one direction across it, and a low resistance for the reverse direction of heat flow. The thermal diode of the luminaire according to the invention is positioned so that it has a high resistance to heat flow from the sunshade to the light emitting element and a low resistance for the reverse direction of heat flow from the light emitting element to the sunshade.
During daylight, for example in countries like Dubai, when the temperature can be more than 40 degrees Celsius, the sunshade prevents that sunlight reaches the light emitting element and that the light emitting element is exposed to excessive heat. Also other elements of the luminaire, like electronic power supplies and plastic lenses, can be shielded by the sunshade against direct sunlight. During daylight, no heat is transferred by the thermal diode from the second end to the first end at the light emitting element.
During the night, when the light emitting element is being used, the temperature of the light emitting element will get higher than the temperature on a side of the sunshade remote from the light emitting element. Now, the thermal diode will transfer heat from the first end to the second end at the sunshade.
Preferably the sunshade is made of a material, like aluminium or copper, which easily transfers heat over the whole surface of the sunshade so that heat from the thermal diode will be conducted over the whole sunshade.
Another embodiment of the luminaire according to the invention is characterized in that the thermal diode comprises a vapour chamber partly filled with a liquid.
Due to gravity, the liquid will be located near the first end. When the first end is warmer than the second end, liquid in the vapour chamber will evaporate and condense against the second end, thereby releasing the heat to the second end. The condensate will flow back to the first end by the force of gravity. Such a thermal diode is relatively simple and free of maintenance.
Yet another embodiment of the luminaire according to the invention is characterized in that the luminaire comprises an insulation layer located between the light emitting element and the sunshade, wherein the thermal diode extends through the insulation layer from the light emitting element to the sunshade. Due to the insulation layer, heat will be prevented from moving from the sunshade to the light emitting element and vice versa, so that heat can only be transferred in a controlled manner from the light emitting element to the sunshade by the thermal diode. BRIEF DESCRIPTION OF THE DRAWINGS
The invention will be explained in more detail with reference to the drawing, in which:
Fig. 1 is cross section of a first embodiment of the luminaire according to the invention,
Figs. 2A and 2B are enlarged views of the thermal diode of the luminaire as shown in figure 1 ,
Fig. 3 is cross section of a second embodiment of the luminaire according to the invention.
DETAILED DESCRIPTION OF EMBODIMENTS
In the figures, like parts are indicated by the same numerals.
Figure 1 shows a first embodiment of a luminaire 1 according to the invention, which luminaire 1 is used as street lighting. The luminaire 1 comprises a pole 2, a housing 3 connected to the pole 2 and a sunshade 6 located above the housing 3. A light emitting element 4, electronic power supplies 5 and plastic lenses are located in the housing 3. The light emitting element 4 comprises preferably light emitting diodes.
The sunshade 6 comprises a plate of thermally conductive material like aluminum, copper.
Between the housing 3 and the sunshade 6 a layer 7 of thermal insulation material like, mineral wool, polystyrene or other lightweight insulation material is located. The insulation layer 7 can be located against either the housing 3 or the sunshade 6 or against the housing 3 as well as the sunshade 6.
The luminaire 1 also comprises a number of thermal diodes 8, extending through the insulation layer 7 and being thermally connected with a first end 9 via or through the housing 3 to the light emitting element 4 and with a second end 10 to the sunshade 6. The second end 10 is located higher than the first end 9. Each thermal diode 8 comprises a vapour chamber 11 partly filled with a liquid 12 (see figure 2), for example in between 10% and 40% of the volume of the chamber is filled with liquid. If the filling is less than 10%, the amount of liquid tends to be too little to be effective in cooling for long periods. If the filling is over 40%, the space for evaporation of the liquid tends to become too small involving the risk of a build-up of relatively high vapor pressure inside the chamber and possibly requiring additional safety measures, for example to provide the chamber with a safety valve.
During daylight, heat from the sun 13 in the direction of arrow PI will be prevented from reaching the housing 3 and the light emitting element located therein by the sunshade 6 and the insulation layer 7. The second end 10 of the thermal diode 8 will get warmer than the first end 9, so that no evaporation and condensation will take place in the vapour chamber 11. No heat transfer in the direction of arrow P2 will occur.
At night, when the luminaire 1 is being used, the light emitting element 4 will emit light (arrows P3) and will get hot, and the heat will be transferred via the housing 3 in the direction of arrow P4 to the first ends 9 of the thermal diodes 8. Due to the heat, the liquid 10 in the vapour chamber 11 will evaporate in the direction of arrow P5 and condensate against the second end 10 which is cooler than the first end 9, whereby heat is transferred via the second end 10 in the direction of arrow P6 to the sunshade 6.
The vapour chamber 11 can have a cylindrical shape from about 10 millimeter in diameter up to a rectangular shape with the size of the luminaire. A cylindrical shape with a diameter of 10-40 millimeter is preferred. The liquid can be water, alcohol or refrigerant liquids as used in cooling installations.
Figure 3 shows a second embodiment of a luminaire 21 according to the invention, which luminaire 21 is used as street lighting. The luminaire 21 differs from the luminaire 1 in that it comprises a different kind of thermal diode 28 having a second end 30 the size of which is nearly as large as the sunshade 6. The thermal diode 28 comprises a number of smaller first ends 29 extending through an insulation layer 27 and being located against the light emitting element 4. The insulation layer 27 is located against a wall 31 of the thermal diode 28, which wall 31 is located at a level between the first ends 29 and the second end 30.
Other variations to the disclosed embodiments can be understood and effected by those skilled in the art in practicing the claimed invention, from a study of the drawings, the disclosure, and the appended claims. In the claims, words like "comprising" and "having" do not exclude other elements or steps, and the indefinite article "a" or "an" does not exclude a plurality. The mere fact that certain measures are recited in mutually different dependent claims does not indicate that a combination of these measures cannot be used to advantage. Any reference signs in the claims should not be construed as limiting the scope thereof.

Claims

CLAIMS:
1. A luminaire (1, 21) comprising at least a light emitting element (4) and a sunshade (6), characterized in that the luminaire (1, 21) comprises at least one thermal diode (8, 28) being thermally connected with a first end (9, 29) to the light emitting element (4) and with a second end (10, 30) to the sunshade (6), wherein the second end (10, 30) is located higher than the first end (9, 29).
2. A luminaire (1, 21) according to claim 1, characterized in that the thermal diode (8, 28) comprises a vapour chamber (11) partly filled with a liquid (12).
3. A luminaire (1, 21) according to claim 1 or 2, characterized in that the luminaire (1, 21) comprises an insulation layer (7, 27) located between the light emitting element (4) and the sunshade (6), wherein the thermal diode (8, 28) extends through the insulation layer (7, 27) from the light emitting element (4) to the sunshade (6).
PCT/IB2011/055553 2010-12-17 2011-12-08 A luminaire WO2012080917A2 (en)

Applications Claiming Priority (2)

Application Number Priority Date Filing Date Title
EP10195548.2 2010-12-17
EP10195548 2010-12-17

Publications (2)

Publication Number Publication Date
WO2012080917A2 true WO2012080917A2 (en) 2012-06-21
WO2012080917A3 WO2012080917A3 (en) 2012-11-01

Family

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Family Applications (1)

Application Number Title Priority Date Filing Date
PCT/IB2011/055553 WO2012080917A2 (en) 2010-12-17 2011-12-08 A luminaire

Country Status (1)

Country Link
WO (1) WO2012080917A2 (en)

Citations (1)

* Cited by examiner, † Cited by third party
Publication number Priority date Publication date Assignee Title
GB2464518A (en) 2008-10-20 2010-04-21 Sensitive Electronic Co Ltd Outdoor light emitting diode lamp with sunshade

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US3112890A (en) * 1961-05-16 1963-12-03 Charles D Snelling Fluorescent lamp fixture
US3517181A (en) * 1967-07-27 1970-06-23 Structural Electric Products C Inset high intensity light and cooling means therefor
TWI303302B (en) * 2005-10-18 2008-11-21 Nat Univ Tsing Hua Heat dissipation devices for led lamps
US7806563B1 (en) * 2006-08-17 2010-10-05 Intencity Lighting, Inc LED cooler apparatus and method of use
CN100583470C (en) * 2006-12-15 2010-01-20 富准精密工业(深圳)有限公司 LED radiating device combination
CN101469819A (en) * 2007-12-27 2009-07-01 富准精密工业(深圳)有限公司 LED lamp
US7674012B1 (en) * 2009-04-17 2010-03-09 Cpumate Inc. LED lighting device capable of uniformly dissipating heat

Patent Citations (1)

* Cited by examiner, † Cited by third party
Publication number Priority date Publication date Assignee Title
GB2464518A (en) 2008-10-20 2010-04-21 Sensitive Electronic Co Ltd Outdoor light emitting diode lamp with sunshade

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Publication number Publication date
WO2012080917A3 (en) 2012-11-01

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