Heat sink

Details Heat sink Heat sink

1998-03-23

2001-03-06

Flanigan, Allen (Department: 3743)

Heat exchange

With retainer for removable article

Electrical component

C165S185000, C361S704000

Reexamination Certificate

active

06196298

ABSTRACT:

FIELD OF THE INVENTION
This invention relates to a heat sink, particularly a heat sink to dissipate heat from a lamp, camera or the like.
BACKGROUND OF THE INVENTION
The invention will for convenience be more specifically described below with particular reference to a lamp although it will be appreciated that it is not intended to be so limited and, indeed, has widespread applicability.
Heat sinks to dissipate heat from lamps and the like are well known and it is an object of the present invention to provide a heat sink that can improve heat dissipation from a source while maintaining or reducing the overall size of the heat sink. Thus, in comparison with prior heat sinks, the invention enables an increase in the effective surface area available for heat dissipation within a given overall volume.
SUMMARY OF THE INVENTION
Accordingly the invention provides a heat sink comprising a cylindrical core of thermally conducting material and an array of spaced, heat dissipating fins extending around and attached to the outer surface of the core, the fins being disposed at an angle to the longitudinal axis of the core and the heat sink containing a recess to accommodate a portion of the body requiring heat dissipation whereby the body can be in contact with the core.
The recess is preferably shaped and sized to receive the body closely to ensure good contact between the body and the core to maximise the heat dissipation effect.
The core is preferably of copper although other good thermal conductors, e.g. aluminium or silver, may be used if desired.
The recess may be in the core itself. In this embodiment the recess may extend for the whole of the axial length of the core, i.e. the core may be an annulus, and the recess is in fact a through passage, or it may extend only partially along the length of the core. In this latter embodiment the core may be a solid cylindrical bar of, e.g. copper, having an integral hollow annular portion at one end to define the recess. Alternatively, the recess may be defined by the fins only. Thus the fins may extend axially beyond the core to define the recess. In this case, the only direct contact between the lamp or other body and the core is an end to end contact at the inner end of the recess and there may also be direct contact between the lamp and the fins. Preferably in this latter embodiment, the recess defined by the fins shares a longitudinal axis with the core and hence extends centrally in the heat sink.
The fins, which are preferably of the same material as the core, may be attached to the core by any suitable means. Thus adhesives or low temperature soldering or high temperature brazing may be used for copper and adhesives or vacuum brazing may be used for aluminium. Suitable adhesives include resin-based adhesives, e.g. epoxy resins. To achieve the desired angling of the fins, correspondingly angled slots may, for example, be machined on the surface of the core, each slot to receive an edge of a fin. Alternatively, the core may be formed by casting with appropriate slots. It may be preferable to cast the core and fins or a proportion of the fins, e.g. alternate fins, as an integral body. Thus, for example, a repeating array of fin then slot then fin may be cast with alternate separate fins then being adhered into the slots.
The angle of the fins to the longitudinal axis of the core may be, for example from 30° to 75°, especially from 40° to 60°.
In one embodiment the fins have an axial extent (relative to the core) equal to the length of the core and are co-extensive axially with the core. However, this is not essential and, if desired, the fins may extend beyond one or both ends of the core. Indeed, as indicated above, this arrangement in which the fins extend beyond one end of the core forms one particular embodiment of the invention when the core is a solid bar.
It will be appreciated that when a lamp or other heat source is positioned in the recess, that portion of the surface of the lamp within the recess is surrounded by the core and/or the fins and is in contact with the core and possibly the fins. Thus heat is rapidly and effectively passed by conduction through the core to the fins with, possibly, some conduction directly to the fins as indicated above, and thereby dissipated to atmosphere. The angled arrangement of the fins enables the effective surface area through which the heat is dissipated to be maximised for a given overall volume of heat sink.
The heat sink may, of course, be used in conjunction with other means conventionally used to dissipate the heat transmitted through the fins, e.g. forced draughts of air.
As indicated above, although the invention is described herein with particular reference to lamps, it is applicable to a variety of other heat sources, e.g. lasers, studio lighting and, particularly, any cylindrically-shaped heat source. Thus the recess will normally be cylindrical although other shapes of recess may be provided, if desired, to match other shapes of heat sources.


REFERENCES:
patent: 2289984 (1942-07-01), Mouromtseff et al.
patent: 2680009 (1954-06-01), Nekut
patent: 4689659 (1987-08-01), Watanabe
patent: 4785216 (1988-11-01), Roberts et al.
patent: 5561338 (1996-10-01), Roberts et al.
patent: 5785116 (1998-07-01), Wagner
patent: 3151838 A1 (1983-07-01), None
patent: 0 751 339 A2 (1997-01-01), None

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