Abstract
A finned heat sink (1) comprising a stack of N finned heat sink plates (3). The N finned heat sink plates comprise a top plate (3a) on top of a bottom plate (3b) and optionally at least one sandwiched plate (3c). The bottom plate (3b), the top plate (3a) and the sandwiched plate (3c) comprise a heat dissipating fin (9) and an opening (7). The fins (9) are bent out of plane of the plates (3). The fin (9) of the bottom plate (3b) and the sandwiched plate (3c) extend through the opening (7a) in the top plate (3a) in the same direction as the fin (9a) of the top plate (3a).
Claims
1. A finned heat sink comprising: a plurality of N heat sink plates including at least a bottom plate and a top plate, each of the heat sink plates including at least two heat dissipating fins, wherein a first edge of each heat dissipating fin is bent out of a plane of the respective heat sink plate, each heat sink plate further includes a base part with an opening, wherein the base part of the top plate is on top of the base part of the bottom plate and wherein a heat dissipating fin of the bottom plate is bent and extends through the opening in the top plate, a heatsink base wherein the plurality of N heat sink plates are mounted, wherein each heat sink plate has a thickness T and the heatsink base comprises a profile step with a profile size Ps according to the relation
Ps=O/N, wherein O is the distance between two adjacent first edges of the at least two heat dissipating fins in the base part of the top heat sink plate transverse to the first edge, and Ps is measured along the plane P of the base part of the top heat sink plate in a direction transverse to the first edge, each step having a height H essentially equal to said thickness T.
2. The finned heat sink as claimed in claim 1, wherein for each heat sink plate, the heat dissipating fins have a perimeter comprising a first edge part, said heat dissipating fins being cut out from the base part over said perimeter except for said first edge part.
3. The finned heat sink as claimed in claim 1, wherein the plurality of N heat sink plates comprises a sandwiched plate located in between the top and bottom plate, a fin of the sandwiched plate extends through the opening of the top plate.
4. The finned heat sink as claimed in claim 1, wherein the heat dissipating fins have a surface area essentially of a size equal to a size of the opening bordered by the first edge of said respective fin.
5. The finned heat sink as claimed in claim 1, wherein the heat dissipating fins of the heat sink plates are spaced apart by a spacing S according to the relation
S=O/N, wherein O is the distance between two adjacent first edges of the at least two heat dissipating fins in the base part of the top heat sink plate transverse to the first edge, and S is measured along the plane of the base part of the top heat sink plate in a direction transverse to the first edge.
6. The finned heat sink as claimed in claim 1, wherein the heat sink plates abut each other with the base parts and are mutually fixed.
7. The finned heat sink as claimed in claim 1, wherein a heat conducting filler material is provided in between the heatsink base and the base parts of adjacent heat sink plates.
8. The finned heat sink as claimed in claim 1, wherein N is in the range of 2 to 10.
9. The finned heat sink as claimed in claim 1, wherein the openings formed by the bending of material out of the plane of the respective heat sink plate to form a single fin of the heat dissipating fins, is larger than the respective single fin.
10. The finned heat sink as claimed in claim 1, wherein a single opening is formed by bending material out of plane of the heat sink plate to form a plurality of fins of the heat dissipating fins.
11. A lighting device comprising a finned heat sink according to claim 1.
12. Lighting device as claimed in claim 11, wherein the lighting device is a LED lamp.
13. The finned heat sink as claimed in claim 1, wherein N is in the range of 3 to 6.
Description
BRIEF DESCRIPTION OF THE DRAWINGS
(1) The invention will now be further elucidated by means of the schematic drawing, in which the dimensions of some parts might be exaggerated for the sake of clarity. The drawing is intended to show the principle of the invention and is by no means intended to limit the invention to the given embodiments. The number of certain parts, for example fins, openings and stacked heat sink plates, given in the embodiments can be lower or higher. In the drawing:
(2) FIG. 1 shows a perspective view of a finned heat sink plate according to the prior art;
(3) FIG. 2a shows a perspective view of a single heat sink plate to be used in a first embodiment of a finned heat sink according to the invention with stacked heat sink plates as shown in FIG. 2c;
(4) FIG. 2b shows an intermediate stage of assembling the stacked heat sink;
(5) FIG. 3 shows a second embodiment of the finned heat sink according to the invention;
(6) FIG. 4a shows a base with a stepped profile of a heatsink according to the invention;
(7) FIG. 4b shows a cross-sectional view of a third embodiment of the finned heat sink according to the invention with the base of FIG. 4a;
(8) FIG. 5 shows a perspective view of a fourth embodiment of the finned heat sink according to the invention.
(9) FIG. 6a shows an embodiment of a heat sink plate with multiple rows of fins;
(10) FIG. 6b shows a heat sink comprising two stacked fin plates of FIG. 6a;
(11) FIG. 6c shows the construction of a larger heatsink from overlapping tiling of the heat sink plates of FIG. 6a;
(12) FIG. 7 shows an embodiment of a heat sink plate with a fin smaller than the opening;
(13) FIG. 8 shows an embodiment of a heat sink plate with one longitudinal side strip removed;
(14) FIG. 9a shows an embodiment in a lighting device application with fins to the opposite side of a heat sink with respect to a light source, and
(15) FIG. 9b shows an embodiment with fins and light source both at the same side of the heat sink and with fins at the side opposite of the heat sink with respect to the light source.
DESCRIPTION OF PREFERRED EMBODIMENTS
(16) FIG. 1 shows a perspective view of a stamped, finned heat sink 1 according to the prior art. The heat sink comprises only one heat sink plate 3 plate, said plate has a base part 5 with four openings 7 and equally sized four fins 9. From each opening one rectangular fins has been punched along three sides 10 of a perimeter 11 of each fin. A first edge 13 of the perimeter remains un-punched and each fin is bend over said first edge out of plane P of the base part to extend at an acute angle to said plane. This known heat sink involves the disadvantages that its thermal cooling functioning is relatively low and that it can only be suitably applied for low aspect ratio finned surfaces where the fin height is less than the fin distance.
(17) FIG. 2a shows a perspective view of a single heat sink plate 3 used in a first embodiment of a finned heat sink according to the invention. The single heat sink plate shown in FIG. 2a is quite similar to the known finned heat sink, i.e. said plate has a base part 5 with five openings 7 and equally sized five fins 9. From each opening one rectangular fins has been punched along three sides of a perimeter 11 of each fin. A first edge 13 of the perimeter 11 remains un-punched and each fin is bend over said first edge out of plane P of the base part to extend essentially transverse to said plane P. The fins have a size of 130*50 mm and are punched out of an anodized aluminum plate of 150*300 mm of 1 mm thickness, the distance O between two adjacent first edges in the base in the direction perpendicular to said first edges are of the dimension as the fin plus the width of a bridge base part 14, in the figure 60 mm. The fins on this single heat sink plate also have a mutual equidistant spacing of 60 mm. This means that base portions in between two adjacent fins, i.e. the bridge parts 14, have a size (width) in the direction perpendicular to the first edge of 10 mm.
(18) FIG. 2b shows an intermediate stage of assembling the stacked configuration of the first embodiment of a heat sink 1 with the protrusion of fins 9b of bottom plate 3b and fins 9c of intermediate plates 3c plate through the openings 7a in the top plate 3a and openings 7c of the intermediate plates 3c.
(19) FIG. 2c shows the assembled stage of a first embodiment of a finned heat sink 1 according to the invention and comprises a stacked configuration of N heat sink plates 3 of FIG. 2a wherein N=4. The stack comprises a top plate 3a, a bottom plate 3b and two sandwiched plates 3c in between said top and bottom plate. Fins 9b,9c of the plates below the top plate all extend through openings 7a in the top plate, the fins 9b of the bottom plate extends through the openings 7c in the sandwiched plates and the openings in the top plates. In short, fins of a lower plates extend to openings of plates on top of said lower plate. Furthermore, the fins are all equidistantly spaced at a spacing S of O/N=60 mm/4=15 mm, i.e., in a direction transverse to the first edges 13 and all extend essentially in the same direction from the base part 5 and at the same side of the top plate.
(20) FIG. 3 shows a second embodiment of the finned heat sink 1 according to the invention comprising stack of three heat sink plates 3. Each heats sink plate comprises openings 7 and fins 9 which each are arranged in two parallel rows 17. The first edges 13 of the fins, which also form the base of the fins, are arranged equidistantly at distance Db. However, the angle at which the fins extend from the base part 5 gradually decreases from =90 for central fins 8c, via intermediate fins 8b to most outer fins 8a which extend at 60. In the embodiment of FIG. 3 a distance Dt between top edges 15 of the fins is larger on average than the distance Db of the fins at their first edge 13, i.e. the distance between the fins widens from first edges towards top edges of the fins. The heat sink in the figure is made of high a temperature resistant and thermal conductive plastic or polymer, for example Coolpoly, polyphenylenesulfide (PPS), or Vespel-SP22 comprising 40% graphite.
(21) FIG. 4a shows a heatsink base 21 with a stepped profile 20. The stepped profile comprises profile steps 19. FIG. 4b shows a cross-sectional view of a third embodiment of the finned heat sink 1 according to the invention and comprises a stacked configuration of N heat sink plates 3a-c wherein N=4. The stack comprises a top plate 3a, a bottom plate 3b and two sandwiched plates 3c in between said top and bottom plate. Fins 9b,9c of plates below the top plate 9a all extend to all openings 7a,7c of plates on top of said lower plates. The heat sink base 21 of the heat sink comprises the profile step 19 with a profile size Ps according to the relation
Ps=O/N, wherein
(22) O is the distance between two adjacent first edges 13 in the base part of the top heat sink plate 3a transverse to the first edge, and Ps is measured along the plane of the base part of the top heat sink plate in a direction transverse to the first edge. The heat sink plate has a thickness T and so have the base part 5 and the fins 9. Each profile step 19 has a height H essentially equal to said thickness T. Between the heat sink base and the heat sink plates a heat conductive filler material 24 is provided to reduce the through plane resistance Rth.
(23) FIG. 5 shows a perspective view of an embodiment of a single heat sink plate 3 to be used in a fourth embodiment of a finned heat sink according to the invention. The single heat sink plate has a base part 5 with four openings 7 and eight fins 9. Each opening 7 is bordered a.o. by side strips 6a. From each opening two rectangular, neighboring fins 9e,9f have been punched along three sides of a perimeter 11 of each fin. The neighboring two fins together have the same size as the size of the opening. A first edge 13 of the perimeter 11 remains un-punched and each fin is bend over said first edge out of plane P of the base part to extend at a specific angle or to said plane. The fins 9e extend at an angle with the base part 5, with 75 and the fins 9f extend at an angle with the base part, with 105.
(24) FIG. 6a shows a single heat sink plate 3 with multiple parallel rows of fins 9 and openings 7, said heat sink plate can be used as an elementary heat sink plate as will be discussed below. Two neighboring fins 9e,9f each have a respective opening 7e,7f. Each opening has a perimeter 11 bordered a.o. by longitudinal side strip 6a and a central strip 6b. Said openings 7e,7f are separated by the longitudinal central strip 6b.
(25) FIG. 6b shows a stack of two heat sink plates 3 of FIG. 6a. In FIG. 6b the two plates are stacked such that they overlap about maximally, i.e. they have practically full overlap. In FIG. 6c tiling and another stacking of the heat sink plates 3 of FIG. 6a is shown. It is shown that four adjoining heat sink plates 3p are positioned or tiled in a two by two matrix arrangement mutually abutting each other. A fifth heat sink plate 3q is stacked on top of said four heat sink plates 3p and made to partially overlap with each of said four heats sink plates. The overlapping is shown only for one heat sink plate 3q, but as can be easily envisaged, more heat sink plates can be used in this way to create an even larger combined heat sink plate. Thus a combined heat sink can be created by a number of elementary heat sink plates, said combined heat sink plate has a larger size than the size of an elementary heat sink plate.
(26) FIG. 7 shows another embodiment of a heat sink plate 3 where the fin 9 is smaller than the opening 7. In this specific embodiment the fin is tapering from first edge 13 to top edge 15 rendering some waste parts 99 but also rendering the advantages that the fins can more easily bent out of plane P of the base part 5 of the heat sink plate as well as that stacking of multiple heats sink plates is facilitated.
(27) FIG. 8 shows an embodiment of a heat sink plate 3 according to the invention in which one longitudinal side strip 6a, indicated in phantom, of the base part 5 of the heat sink plate is removed. Thus, openings 7 with an open side 28 are obtained and a sideways assembly and stacking of multiple heat sink plates is enabled.
(28) FIG. 9a shows an embodiment of the heat sink 1 according to the invention mounted and applied in a lighting device 29. In the lighting device the fins 9 of the heat sink are located at an opposite side of the heat sink base 21 with respect to a light source 25. In FIG. 9a the lighting device is a LED lamp according to the invention comprising the LED light source 25 mounted on the heat sink base. A similar construction as shown in FIG. 9a can be applied in a LED luminaire. The finned heat sink plates 3 are firmly mutually attached and to base 21 via screws 27 resulting in an increased (thermal) contact between the heatsink base 21 and base parts 5 of adjacent stacked heat sink plates 3, thus further reducing Rth.
(29) FIG. 9b shows a similar embodiment of a LED lamp 29, made out of copper metal laminated graphite sheet, and with an alternative configuration of heat sinks 1, i.e. the heat sink has additional heat sink plates 3 on the side of the LED light source, creating a finned stacked heatsink with fins 9y in extending away from the heatsink base 21 at the side on which the LED light source is mounted, and in an opposite (perpendicular) direction thereto, fins 9x that extend away from the LED light source at a side of the heat sink base facing away from the LED light source. Furthermore, the eight fins 9x at a side of the heats sink base facing away from the light source are mutually mechanically joined through a slotted plate 30, for example an aluminum plate, increasing the mechanical stability of the fin package.
