A modular heatsink system for a lighting device

Abstract

A modular heatsink system (3a, 3b, 3c) for a lighting device (1). The modular heatsink system (3a, 3b, 3c) comprises a number of heatsink modules (3b, 3c) that are adapted to me mounted on a platform (2) around a central heatsink module (3a). The number of modules mounted can be adapted to the match the number of light sources fitted to the platform (2).

Description

[0001] A MODULAR HEATSINK SYSTEM FOR A LIGHTING DEVICE

[0002] FIELD OF THE INVENTION

[0003] The present invention relates to lighting devices in particular to outdoor luminaries with adjustable lumen output, and in particular with the adaptation of heatsinks to a specific lumen output.

[0004] BACKGROUND OF THE INVENTION

[0005] Lighting devices for outdoor use e.g. luminaries places along a road as streetlights or to illuminate open public places are typically subject to aesthetic constraints. That is to say, the lighting devices should have a harmonized or identical appearance. This also applies when not in use, i.e. during daytime. However, the lumen output needed at nighttime need not be the same for all luminaires, that is to say the illumination of one street may differ from another or from that of a public place within one community where the same appearance is desired. Evidently, differences could differ even more between communities which have incidentally chosen to use the same lighting devices. The adjustment to the required lumen output can be adjusted by using an appropriate number of light sources. This should preferably be possible in situ, so that a luminaire fitted at e.g. the top of an existing pole can be retrofitted with additional light sources, or superfluous light sources be removed without taking the luminaire down. Light sources using LEDs such as COBs (Chip on Board devices), however, require cooling and increased number of COBs consequently require an increased amount of heatsink area if one is to maintain passive cooling. In this respect US2015 / 0260391 discloses a modular light assembly where the length of the light assembly may be adapted by using a selected number of identical lighting units next to each other along the length of the lighting assembly, so as to maintain the same general, but not identical, appearance of light assemblies with different lumen output. Each module comprises heatsinks corresponding the power of the light source, so more light sources added automatically means more heatsink area.

[0006] This modular approach alters the appearance of the light assemblies so two neighbouring luminaries may not have the same appearance. Although, US2015 / 0260391 makes reference to the modular build as a platform, it doesn’t really apply one and the same platform. In manufacturing is it generally advantageous to keep the number of basic elements of an assembly to a minimum. Together with the desire to provide the aesthetic appearance identical luminaries there is thus a need to provide one and the same platform with a number of light sources necessary for the specific illumination purpose while at the same time providing the necessary heatsink area for the cooling, in particular by altering the both the number of light sources and the heatsink area in situ.

[0007] SUMMARY OF THE INVENTION

[0008] It is an object of the present invention to overcome this problem, and to provide a luminaire where the heatsink area may readily be changed in order to adapt the heatsink area to changes in luminous output.

[0009] According to a first aspect of the invention, this and other objects are achieved by a lighting device comprising a platform accommodating a lighting unit and a modular heatsink arrangement, the platform comprising a body with a first surface area facing in a first direction and a second surface facing in a second direction, where the lighting unit is arranged on the first surface area and a first heatsink module of the modular heatsink arrangement is arranged at a central location on the second surface area, where the size of the first surface area is adapted to accommodate a number of further lighting units and where shape of the first heatsink module and the size of the second surface area surrounding the first heatsink module is adapted to receive further heatsink modules surrounding the first heatsink module.

[0010] In this way it becomes possible to scale up or down the lumen output by adding more or less light units and at the same time there is room provided for adapting the required cooling area of the heatsink by using more or less heat sink modules.

[0011] According to a second aspect of the invention the objects are achieved by a modular heatsink system comprising a first heatsink module adapted to be arranged on a surface in a lighting device, and at least one second heatsink module adapted to be arranged on the surface, where the first heatsink module comprises a first interconnected arrangement of fins extending away from the surface when the first heatsink module is mounted thereon and the second heatsink system comprises a second interconnected arrangement of fins extending away from the surface when the second heatsink module is mounted thereon, where the second interconnected arrangement of fins forms a closed geometry so as to surround the first heatsink module in all directions on the surface. According to a third aspect of the invention, the objects are achieved by a lighting system comprising a lighting device according to the first aspect of the invention and a modular heatsink system according to the second aspect of the invention.

[0012] According to an embodiment of the first aspect of the invention the lighting device comprises at least one second heatsink module. This allows the additional heat dissipation when further lighting modules are added.

[0013] According to an embodiment of the first aspect of the invention the second heatsink module surrounds the first heatsink module on said second surface area. This makes the placement of the further heatsink module intuitive when mounting and allows for good thermal contact in the cross-wise or radial direction across the first and second surface areas.

[0014] According to an embodiment of the first aspect of the invention, the first heatsink module and the second heatsink module are in mechanical contact. The mechanical contact supports the thermal contact in the cross-wise or radial direction across the first and second surface areas, so that the heat may flow in the radial direction between a first interconnected arrangement of fins and a second interconnected arrangement of fins.

[0015] According to an embodiment of the first aspect of the invention, the first heatsink module and the second heatsink module are arranged in a concentric manner on the second surface. This, in turn, aids in the intuitive placement and facilitates the flow of heat in the radial direction between the first and second heatsink modules.

[0016] According to an embodiment of the first aspect of the invention, the second surface is provided with locating means for positioning the first and / or further heatsink modules. Having such locating means aids in the quick, correct precise placement of the first and second heatsink modules, in turn, allowing good mechanical contact and hence flow of heat in the radial direction between the first and second heatsink modules.

[0017] According to an embodiment of the first aspect of the invention, the locating means are bores adapted to receive a threaded fastener. Thus, in situ, heatsink modules may easily be placed in the correct location and in good mechanical and thermal contact with the first or second surface areas, respectively, of the platform.

[0018] According to an embodiment of the second aspect of the invention, the first heatsink module comprises a first outer continuous fin. The first outer continuous fin allows good mechanical and thermal contact with the with the second heatsink module, in particular when according to a further embodiment, the second heatsink module comprises an inner continuous fin and a second outer continuous fin interconnected by a number of connecting branch fins. According to an embodiment of the second aspect of the invention, the connecting branch fins extend along a wave-shaped path on the surface when the second heat sink module is mounted on the surface. Having the fins in a waveshape to follow a waveshaped path in the radial direction increases the heat dissipation area as compared to straight fins with the same end point.

[0019] According to an embodiment of the second aspect of the invention, the inner continuous fin of the second modular heatsink module is adapted to mechanically engage the first outer continuous fin of the first heatsink module. This, in turn, aids in the intuitive placement and facilitates the flow of heat in the radial direction between the first and second heatsink modules.

[0020] According to an embodiment of the second aspect of the invention, at least one of the first outer continuous fin of the first heatsink module, the inner continuous fin of the second heatsink module and the second outer continuous fin of the second heatsink module is ring-shaped. Rings are readily positionable.

[0021] It is noted that the invention relates to all possible combinations of features recited in the claims.

[0022] BRIEF DESCRIPTION OF THE DRAWINGS

[0023] This and other aspects of the present invention will now be described in more detail, with reference to the appended drawings showing embodiment(s) of the invention. In the drawings:

[0024] Fig. 1 shows a top view of a lighting device fitted with a modular heatsink system according to the invention,

[0025] Fig. 2 shows a side view of the lighting device of Fig. 1,

[0026] Fig. 3 schematically shows a bottom view of the lighting device according to the invention fitted with a single light unit, and

[0027] Fig. 4 shows an exploded perspective view of a lighting device with the modular heatsink system of Fig. 1.

[0028] Fig. 5 shows a partially exploded view of the modular heatsink arrangement 3 a, 3b, 3 c on the lighting device of Fig. 1.

[0029] As illustrated in the figures, the sizes of layers and regions are exaggerated for illustrative purposes and, thus, are provided to illustrate the general structures of embodiments of the present invention. Like reference numerals refer to like elements throughout. DETAILED DESCRIPTION

[0030] The present invention will now be described more fully hereinafter with reference to the accompanying drawings, in which currently preferred embodiments of the invention are shown. This invention may, however, be embodied in many different forms and should not be construed as limited to the embodiments set forth herein; rather, these embodiments are provided for thoroughness and completeness, and fully convey the scope of the invention to the skilled person.

[0031] Fig. 1 shows a top view of a lighting device 1 fitted with a modular heatsink system 3a, 3b, 3c according to the invention. The lighting device 1 comprises a platform 2 and an electronics housing 4 accommodating electronics etc. of the lighting device 1. The lighting device may also include a top cover 5, in the illustrated embodiment arranged between modular heatsink system 3a, 3b, 3c and the electronics housing 4. As can be seen from Fig. 2 the platform 2 comprises a body with a first surface area 6 facing in a first direction, in the illustrated example a lower surface area facing downward. The platform 2 further comprises a second surface area 7 facing in a second direction, in the illustrated example an upper surface area facing upwards. The first surface area 6 comprises at least a first light unit 8. As can best be seen in the bottom view of Fig. 3 the size of the first surface area is adapted to accommodate not only the first light unit 8 but also further light units 9, illustrated in dashed lines to indicate that they are optional. Preferably, the layout of the first surface area 6 is so that the at least one first light unit 8 is centrally arranged and area around it is sufficient to accommodate a number for further light units 9, e.g. at pre-prepared locations in a manner surrounding, as seen in the plane of the first surface area, the at least one first light unit 8. The light units 8 will preferably be Chip-on-Board light sources (COBs) comprising each a number of Light Emitting Diodes (LEDs).

[0032] The more light units 8 are fitted in the first surface area the more cooling is needed because more light units 8 will produce more waste heat that needs to be dissipated when lit. For that reason, the platform 2 itself is preferably made of a material with good heat conductivity and low density (weight to volume ratio), such as aluminium or aluminium- alloy, so as to allow heat conduction from the first surface area 6 through the body of the platform 2 to the opposite second surface area from where it will be dissipated, primarily by natural convection when the surrounding air is heated. This itself is, however, normally insufficient cooling and heatsinks must added to the second surface area for conducting heat away from the second surface area and increasing the overall surface area in contact with the surrounding air and thus available for heat exchange with the surrounding air.

[0033] Turning now to Fig. 4 what could be considered the basic configuration of the lighting device 1 is shown. Centrally arranged on the second surface area 7 of the platform 2 is a first heatsink module 3a. Space is available on the second surface area 7 around the first heatsink module 3a so that when further heatsink modules 3b, 3c are added around the first heatsink module 3 as the first heatsink module will constitute a central heatsink module.

[0034] The first heatsink module 3 a may be integrally formed directly as a part of the platform 2 so that it extends from the second surface area 7 of the platform at the central location. Preferably, however it is a separate piece adapted to be mounted centrally on the second surface area 7 of the platform 2 in good mechanical and thermal contact with the platform 2, e.g. by means of threaded fasteners, such as screws 10a through lugs 1 la or similar apertures in the first heatsink module 3a. Preferably, the platform 2 is provided with suitable holes 12a adapted to receive the screws 10a. Such holes 12a will furthermore serve as locating means for correct positioning of the first heatsink module 3 a in the central position.

[0035] Turning now to Fig. 5 a partially exploded view of the modular heatsink arrangement 3a, 3b, 3c on the lighting device 1. In the illustrated example the modular heatsink arrangement comprises three heatsink modules, i.e. the first heatsink module 3a, and two further heatsink modules 3b, 3c. The first heatsink module 3a is the central heatsink module, and as will be understood from Fig. 5 in conjunction with Fig, 1 the further heatsink modules 3b, 3c will both surround the central heatsink module 3a, preferably in a co-axial manner. The two further heatsink 3b, 3b modules generally have an annular outline or overall envelope with a central aperture 13b, 13c, respectively, and an outer periphery 14a, 14b, respectively.

[0036] The central aperture 13b of the first further module 3b is adapted in size to match the outer periphery 14a of the central first heatsink module 3a. That is to say, match sufficiently close match to establish good mechanical and thermal contact between the central first heatsink module 3a and the surrounding second heatsink module 3b, possibly with a thin layer of heat conducting paste or tape between the central first heatsink module 3a and the surrounding second heatsink module 3b. Similar to the central first heatsink module 3a, the first further heatsink module 3b may have lugs 1 lb adapted to receive screws 10b in holes 12b. Similarly, the central aperture 13c of the second further heatsink module 3c is adapted in size to match the outer periphery 14b of the first further heatsink module 3 a. That is to say, sufficiently close match to establish good mechanical and thermal contact between the central second further heatsink module 3b and the surrounding second heatsink module 3c, possibly with a thin layer of heat conducting paste or tape between the first further heatsink module 3b and the surrounding second heatsink module 3c. Similar to the central first heatsink module 3a and the first further heatsink module, the second further heatsink module 3c may have lugs adapted to receive screws in holes. It may also have a flange 15 or wall adapted to engage the outer rim 16 of the platform 2, for increased thermal contact surface, in turn making specifically adapted to constitute an outer module.

[0037] It is currently preferred to have only three heatsink modules 3a, 3b, 3b constituting thus an inner heatsink module 3a, a middle heatsink module 3b and an outer heat sink module 3c. It is, however, not excluded that three or more further heatsink modules may be used, i.e. that more than one middle heatsink module matching each other in a similar manner are located between the inner module 3a and the outer module 3c.

[0038] As mentioned above, the first and second further heatsink modules 3b, 3c have a generally annular outline or overall envelope. The central first heatsink module 3a on the other hand rather constituting an overall disc shape. That is of course only from a larger perspective. As will be evident from the Figures, the heatsink modules are rather open interconnected structures of fins. When the heatsink modules 3a, 3b, 3c are mounted on the platform 2, the fins extend perpendicular to the second surface area 7, and form patterns when looked at from that perpendicular direction.

[0039] As can be seen the central first heatsink module 3a comprises a first outer circular fin 17 defining the outer periphery 14a. The first outer circular fin 17 is continuous and forms a full circle. In the radial direction towards the centre of the circle a number of radial fins 18, in casu eight, extend so as join in a star at the centre. The radial fins 18 do not extend strictly in the radial direction, although this is not excluded, but preferably follow curved, wave-shaped and / or otherwise undulated paths, so as to increase the surface area of the radial fins 18 as compared to the aforementioned straight radial fins.

[0040] The first further heatsink module 3b likewise comprises an interconnected structure of fins, comprising a second outer circular fin 19, an inner circular fin 20 and a number of interconnecting radial fins 21. The interconnected structure of fins 19, 20, 21 forms a closed geometry so as to surround the first heatsink module 3a in all directions on the surface when seen in the aforementioned perpendicular direction. Both of the circular fins 19 and 20 are continuous and form full circles. The inner diameter of the inner circular fin 20 of the first further heatsink module 3b is adapted to match the outer diameter of the first outer circular fin 17 of the first heatsink module 3 a for good mechanical and thermal contact. Again, space may exist for heat conduction paste or tape. The second outer circular fin 19 and the inner circular fin 20 are interconnected by a number of radially extending branch fins 21. The increased outer circumference of the second outer circular fin 19 as compared to the second outer circular fin 17 of the first heatsink module 3 a, allow for more branch fins 21 in the first further heatsink module 3b than radially extending fins 18 in first heatsink module 3a, in casu twice as many, i.e. sixteen. Having twice the number, allows the radial heat transmission paths to be uniform in all directions in turn reducing hot spots. Like the radial fins 18 in the first heatsink module 3a, the radially extending branch fins 21 do not extend strictly in the radial direction, although this is not excluded, but preferably follow curved, wave-shaped and / or otherwise undulated paths, so as to increase the surface area of the radial fins 18 as compared to the aforementioned straight radial fins.

[0041] Except for an increased diameter, the second further heatsink module 3c is largely similar to the first further heatsink module 3b. It likewise comprises an interconnected structure of fins, comprising an outer circular fin 22, an inner circular fin 23 and a number of interconnecting radial fins 24. The interconnected structure of fins 22, 23, 24 forms a closed geometry so as to surround the second heatsink module 3b in all directions on the surface when seen in the aforementioned perpendicular direction. Both of the circular fins 22 and 23 are continuous and form full circles. The inner diameter of the inner circular fin 22 of the second further heatsink module 3c is adapted to match the outer diameter of the outer circular fin 20 of the second heatsink module 3b, for good mechanical and thermal contact. Also here, space may exist for heat conduction paste or tape. The outer circular fin 22 and the inner circular fin 23 are interconnected by a number of radially extending branch fins 24. Like the radial fins 21 in the first further heatsink module 3b, the radially extending branch fins 24 do not extend strictly in the radial direction, although this is not excluded, but preferably follow curved, wave-shaped and / or otherwise undulated paths, so as to increase the surface area of the radial fins 24 as compared to the aforementioned straight radial fins. The outer circular fin 23 may have a height variation so as to allow it to extend below the level of the second surface area 7 of the platform 2 along the rim 16 of the platform 2, for increase contact area for heat transmission from the platform 2 to the second further heatsink 3c, possibly also via heat conductive paste or tape. The heatsink modules 3 a, 3b, 3 c may be made of the same material as the platform 2 or other materials fulfilling the required of heat conductivity.

[0042] The person skilled in the art realizes that the present invention by no means is limited to the preferred embodiments described above. On the contrary, many modifications and variations are possible within the scope of the appended claims. For example, the matching shapes need not be circular as the described disc and annuli. Other polygonal shapes including triangles, rectangles, etc. as well as more complex polygons with more sides and with higher complexity such as star-shapes. Likewise, the shape of radially extending ribs need not be straight or undulated in the manner shown in the Figures but could take other shapes. Additionally, variations to the disclosed embodiments can be understood and effected by the skilled person in practicing the claimed invention, from a study of the drawings, the disclosure, and the appended claims. In the claims, the word "comprising" does 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 measured cannot be used to advantage.

Claims

CLAIMS:

1. A modular heatsink system (3a, 3b, 3c) comprising a first heatsink module (3a) adapted to be arranged on a surface (7) in a lighting device (1), and at least one second heatsink module (3b) adapted to be arranged on the surface (7), wherein the first heatsink module (3a) comprises a first interconnected structure of fins (17, 18) extending away from the surface (7) when the first heatsink module (3a) is mounted thereon and the second heatsink module (3b) comprises a second interconnected structure of fins (20, 21, 22) extending away from the surface (7) when the second heatsink module (3b) is mounted thereon, wherein the second interconnected structure (20, 21, 22) of fins forms a closed geometry so as to surround the first heatsink module (3a) in all directions on the surface (7) , wherein the first heatsink module (3a) comprises a first outer continuous fin (17), wherein the second heatsink module (3b) comprises an inner continuous fin (20) and a second outer continuous fin interconnected (19) by a number of connecting branch fins (21), wherein the connecting branch fins (21) extend along a curved, wave-shaped and / or otherwise undulated path on the surface (7) when the second heat sink module (3b) is mounted on the surface (7), and wherein the inner continuous fin (20) of the second modular heatsink module (3b) is adapted to mechanically engage the first outer continuous fin (17) of the first heatsink module (3a).

2. The modular heatsink system (3a, 3b, 3c) according to claim 1, wherein at least one of the outer continuous fin (17) of the first heatsink module (3a), the inner continuous fin (20) of the second heatsink module (3b) and the outer continuous fin (22) of the second heatsink module (3b) is ring-shaped.

3. A lighting system comprising a lighting device (1) and a modular heatsink system (3a, 3b, 3c) according to any one of claims 1-2, wherein the lighting device (1)comprising a platform (2) accommodating a lighting unit (8) and a modular heatsink arrangement (3a, 3b, 3c), the platform (2) comprising a body with a first surface area (6) facing in a first direction and a second surface (7) area facing in a second direction, where the lighting unit (8) is arranged on the first surface area (6) and a first heatsink module (3a) of the modular heatsink arrangement is arranged at a central location on the second surface area (7), where the size of the first surface area (7) is adapted to accommodate a number of further lighting units (9) and where shape of the first heatsink module (3 a) and the size of the second surface area (7) surrounding the first heatsink module (3a) is adapted to receive further heatsink (3b, 3c) modules surrounding the first heatsink module (3a).

4. The lighting device (1) according to claim 3, wherein the first heatsink module (3a) and the second heatsink module (3b) are in mechanical contact.

5. The lighting device (1) according to any one of claims 3 to 4, wherein the first heatsink module (3a) and the second heatsink module (3b) are arranged in a concentric manner on the second surface (7).

6. The lighting device (1) according to any one of claims 3 to 5, wherein the second surface (7) is provided with locating means for (12a, 12b) positioning the first and / or further heatsink modules (3a, 3b, 3c).

7. The lighting device (1) according to claim 6, wherein the locating means are bores adapted to receive a threaded fastener (10a, 10b).

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