Heat exchange – With retainer for removable article – Electrical component
Reexamination Certificate
2001-04-17
2002-09-10
Bennett, Henry (Department: 3743)
Heat exchange
With retainer for removable article
Electrical component
C165S121000, C361S697000, C257S722000
Reexamination Certificate
active
06446707
ABSTRACT:
This invention relates to an active heat sink structure and, more particularly, to such an active heat sink structure that optimizes cooling performance when a number of individual heat sinks are arranged in a side-by-side fashion.
BACKGROUND OF THE INVENTION
The performance of heat-producing electronic, electrical, and other devices is often limited by the heat produced during service. If the heat cannot be dissipated, the temperature of the device increases beyond its operating limit, leading to shutdown or failure. Additionally, the reliability of many devices falls as their temperature increases. Heat dissipation problems are increased when several heat-producing devices are positioned close to each other.
Heat-producing devices are often mounted to heat sink structures to aid in the dissipation of the heat. Heat sink structures may be passive or active. In a typical active heat sink, also sometimes called a turbo cooler, a fan is mounted to a top surface of a heat sink base and directs a flow of air against that surface. The heat-producing device is also mounted to the heat sink base, typically on the opposite bottom surface. Heat flows from the heat-producing device into the heat sink base and to the top surface, and from there to the surrounding air. The air flow from the fan increases the heat transfer rate from the top surface into the surrounding air.
This type of active heat sink structure works well when the heat sink is relatively isolated from other heat sinks. However, the inventor has observed that the efficiency of heat removal is reduced when several of the heat-producing devices mounted to their respective heat sinks are positioned laterally adjacent to each other. The result is that the temperatures of the heat-producing devices are sometimes greater than would be the case for isolated heat sinks.
There is a need for an improved approach to heat sinks that improves their cooling efficiency, particularly when a number of heat-producing devices are mounted laterally adjacent to each other. The present invention fulfills this need, and further provides related advantages.
SUMMARY OF THE INVENTION
The present invention provides an active heat sink structure that achieves improved cooling efficiency, particularly where there are two or more heat sinks arranged together in a laterally adjacent, side-by-side fashion. The present approach is implemented without substantial additional cost in the production of the heat sinks.
In accordance with the invention, an active heat sink structure comprises at least one heat sink. Each heat sink comprises a heat sink base having a top surface with a top surface periphery and a top surface center, and an oppositely disposed bottom surface. The heat sink may be described in relation to a first reference line lying in the top surface and a second reference line lying in the top surface and perpendicular to the first reference line. A plurality of air flow paths are defined on the top surface of the heat sink base. The air flow paths are preferably defined by fins extending outwardly from the top surface of the heat sink base. Substantially all of the air flow paths direct a flow of air from the top surface center toward the top surface periphery and substantially parallel to the second reference line, which thereby serves as a common air-flow direction. An air-flow source, such as a fan affixed to the heat sink base, directs air into the plurality of air flow paths from a location at about the top surface center. There is typically a heat-producing device affixed to the bottom surface of the heat sink base.
The heat sink base may be flat, but it is preferably contoured so that the top surface slopes downwardly and away from the top surface center. That is, a thickness of the heat sink base, as measured by a distance between the top surface and the bottom surface, is greater at the top surface center than at the top surface periphery.
The heat sink structure is operable with a single heat sink. Its greatest advantages are realized, however, where there are at least two heat sinks with their respective top surfaces facing parallel to a third reference line lying perpendicular to the first reference line and perpendicular to the second reference line. The heat sinks lie laterally adjacent to each other along the first reference line. In that instance, the air flow is directed parallel to the second reference line and thence perpendicular to the first reference line so that the air flows of adjacent heat sinks do not impinge upon each other.
A source of the inefficiency observed in conventional planar arrays of side-by-side active heat sinks is the impingement of the cooling air flows of the adjacent active heat sinks. When two air flows of adjacent heat sinks impinge, the interference of the two air flows produces turbulence and a gaseous impedance that reduces the flow rate of each of the air flows. The effectiveness of the cooling air over the affected portions of the two heat sinks is thereby reduced, and the temperature of the heat sink and the cooled device rise. The present approach overcomes this loss of effectiveness by directing the cooling air flows of the adjacent heat sinks parallel to each other (i.e., parallel to the second reference line) so that they do not impinge upon each other and produce an impedance to the air flow. The result is that the heat sinks of the array retain their cooling efficiencies and thence their desired temperature.
Other features and advantages of the present invention will be apparent from the following more detailed description of the preferred embodiment, taken in conjunction with the accompanying drawings, which illustrate, by way of example, the principles of the invention. The scope of the invention is not, however, limited to this preferred embodiment.
REFERENCES:
patent: 4918571 (1990-04-01), Grabbe
patent: 6179046 (2001-01-01), Hwang et al.
patent: 6196300 (2001-03-01), Checchetti
patent: 6244331 (2001-06-01), Budelman
patent: 6295202 (2001-09-01), Tucker et al.
Bennett Henry
Hewlett--Packard Company
McKinnon Terrell
LandOfFree
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