Heat exchange – With retainer for removable article – Electrical component
Reexamination Certificate
2000-04-11
2002-04-23
Lazarus, Ira S. (Department: 3743)
Heat exchange
With retainer for removable article
Electrical component
C165S185000, C361S710000
Reexamination Certificate
active
06374906
ABSTRACT:
TECHNICAL FIELD OF THE INVENTION
The present invention relates to heat sinks and, more particularly, to a heat sink having a movable and captive handle attached thereto.
BACKGROUND OF THE INVENTION
Heat sinks are devices that cool heat sources by drawing heat away from the heat sources and convecting the heat to the surrounding atmosphere. Heat sinks are typically made of a heat conductive material, such as aluminum, magnesium, or copper, and have a base portion with a plurality of cooling fins attached thereto. The base portion serves to draw heat from the heat source into the heat sink. The base portion also spreads and transfers the heat to the cooling fins. The cooling fins provide a large surface area, which facilitates the convection of heat to the surrounding atmosphere.
The size and shape of a particular heat sink depends on its application. For example, the base portion is contoured to match the shape of the heat source and is generally appropriately sized to contact the heat source. In many applications, the heat source is an electronic component, such as an integrated circuit having a planar surface, which requires that the base portion be substantially planar. The amount of surface area on the cooling fins is proportional to the amount of heat that the heat sink is able to convect to the surrounding atmosphere. Heat sinks that are required to remove large amounts of heat from a heat source tend to have many cooling fins. The cooling fins provide a large surface area that convects large amounts of heat to the surrounding atmosphere.
Heat sinks are typically fabricated from metals, which provide good thermal conductivity and are relatively easy to fabricate into heat sinks. Metal heat sinks are also durable, which permits them to be securely fastened directly to the heat source. Metals, however, tend to be relatively heavy, making larger heat sinks relatively heavy.
Some heat sinks are used to cool heat-generating electronic components located within various electronic devices. The trend in the design of many of these electronic devices is to reduce the size and weight of the electronic devices and increase their capabilities, which generally increases their power consumption. The increased power consumption in conjunction with the smaller sized electronic devices causes the electronic devices to generate greater amounts of heat within smaller confines, which increases the heat density. Thus, the heat sinks used within these electronic devices have to be relatively large in order to convect the increased amount of heat generated by these electronic devices, which is contrary to the design objective of reducing the size of electronic devices. In addition, the large heat sinks increase the weight of the electronic devices, which is also contrary to the design objective of reducing the weight of electronic devices.
Another problem with large heat sinks is that they tend to be rather cumbersome to install within the small confines of small electronic devices. For example, the heat sinks may be difficult to hold in a fixed location as they are being secured within the electronic device by various hardware components, e.g., screws. As a further example, a heat sink may be secured within the electronic device by the use of a plurality of screws, washers, and nuts. During installation or removal of the heat sink, the screws, washers, and/or nuts may fall into the electronic device, which may cause other components of the electronic device to electrically short. Furthermore, heat sinks may damage components located within the electronic devices during their installation and removal. For example, if a large metal heat sink strikes a wire or electronic component during installation or removal, the wire or electronic component may become damaged, which may, in turn, render the electronic device inoperable.
Another problem with some heat sinks is that they become too hot to manually handle during their operation. This presents a problem if a hot heat sink must be removed from the electronic device. For example, if the heat sink must be removed in order to service the electronic device, the electronic device must be powered down and rendered inoperable for a period during which the heat sink cools. This period of inoperability of the electronic device may be burdensome to the user of the electronic device.
Therefore, a need exists for a cooling device that is able to convect a large amount of heat to the surrounding atmosphere, that is relatively easy to install within and remove from an electronic device, and that occupies minimal space.
SUMMARY OF THE INVENTION
The invention is directed toward a cooling device having a movable handle attached thereto. The cooling device may comprise a heat sink having a base portion and at least one cooling fin attached to the base portion. The handle may be attached to the base portion by the use of captive fasteners, such as captive screws. The captive fasteners may also serve to fasten the cooling device to a heat-generating device which the cooling device serves to cool. As the heat sink is fastened to the heat-generating device, the handle is drawn into close proximity to the heat sink by the fasteners. Thus, the space occupied by the cooling device is reduced as the heat sink is fastened to the heat-generating device.
In a further embodiment of the cooling device, detent mechanisms, such as springs, may be located between the heat sink base portion and the handle. The detent mechanisms may apply a force between the base portion and the handle, which serves to retain the handle in a fixed position relative to the heat sink prior to the heat sink being fastened to the heat-generating device. The detent mechanisms may also serve to apply a constant force between the heat sink base portion and the heat-generating device when the heat sink is fastened to the heat-generating device. This constant force assures that the base portion remains in thermal contact with the heat-generating device as both are subject to different amounts of physical shock and thermal expansion and contraction.
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Artman Paul T.
Coxe William K.
Peterson Eric C.
Duong Tho Van
Hewlett--Packard Company
Lazarus Ira S.
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