Forced-air cooling of a transceiver unit

Details Forced-air cooling of a transceiver unit Forced-air cooling of a transceiver unit

2002-08-29

2003-12-23

Thompson, Gregory (Department: 2835)

Electricity: electrical systems and devices

Housing or mounting assemblies with diverse electrical...

For electronic systems and devices

C165S080300, C165S122000, C361S690000, C361S715000, C361S735000, C454S184000

Reexamination Certificate

active

06667883

ABSTRACT:

FIELD OF THE INVENTION
The present invention relates to heat dissipation. More specifically, the invention relates to heat dissipation in racked electronic devices.
BACKGROUND OF THE INVENTION
Some electronic devices, such as transceivers are mounted on poles or masts outside buildings next to antennas for better system gain since the cables are shorter in length. Longer cables equals less gain and more loss. However, some users may prefer to have the electronic devices, such as the transceivers, racked inside a building for use in wireless networking equipment and for convenience. For example, the cables are shorter in length and therefore less loss is realized. Moreover, the electronic device is out of the elements and in a controlled enviroment where it is easier to service if it should malfunction. However, once out of the elements, there needs to be a way to keep the electronic device cooled while racked.
Long-term protection of sensitive circuits and electronic components is important in many of today's delicate and demanding electronic applications. With the trend toward smaller and more compact electronic modules, the need for thermal management is growing.
The heat that is generated by an electronic device must be transferred away from the electronic device or the performance of the electronic device(s) will deteriorate. The problem of dissipating heat from electronic devices becomes difficult when the circuit board within the electronic device is mounted within a housing. For example, fiber optic transmitter/receiver modules that include circuit boards are often environmentally sealed in a housing to prevent damage from the elements. As a result, the ability to dissipate heat from the electronic devices mounted on the circuit boards becomes challenging. The environmental housing's only mode of heat transfer to the ambient is natural convection. The transmitter/receiver module's only mode of heat transfer to the environmental housing is conduction.
Integrated circuit devices, such as microprocessors, DRAMs, and ASICs may contain millions of transistors. These integrated circuit devices, which may be mounted directly on a support structure (e.g., printed wiring boards or ceramic boards) or encapsulated in plastic packages, generate large amounts of heat during operation. Heat increases a device's electrical resistance, which slows down the device and may affect the device's overall performance. Heat also accelerates wear and tear on the device and may reduce a device's overall life expectancy. Metal can also cause corrosion of metal liners used in the integrated circuit. These factors make adequate heat dissipation important to system performance. Therefore, it is desirable to remove heat from electronic devices and generally keep them as cool as possible during operation.
Heat is both a chemical and physical property of matter and a fundamental component of electronic devices. Heat moves through solid materials by radiation and conduction and through fluids by convection. Conductive heat transfer occurs when energy exchange takes place by direct impact of molecules from a high temperature region to a low temperature region. Heat is moved directly from one material to another with which it is in contact. Heat travels through material like metal, stone, brick and wood very easily, but heat travels relatively slowly through materials like fiberglass or dry foam. In highly conductive materials, heat will move as vibrations directly along the continuous metallic or crystalline bonds. In more resistant materials, the molecular bonds do not vibrate as freely and they are interrupted. When the position of heat particles is less restrained, the more powerful the heat transfer convection process.
To accomplish the objective of heat conduction, it has been conventional practice to use very complex and expensive chassis-integrated heat transfer structures. Another practice is to use more thermally robust circuit components, which undesirably add substantial bulk to the overall housing assembly and is costly. However, there is currently no way to efficiently dissipate heat when devices are stacked.
Thus, there remains a need for an efficient way to dissipate heat from multiple electronic devices. More specifically, there is a need for an efficient way to dissipate heat in stacked electronic devices.
BRIEF DESCRIPTION OF THE INVENTION
The present invention provides for cooling a plurality of racked electronic devices having a first electronic device having at least one cooling vent at a first end and a plurality of cooling holes at a top, each of the cooling vents having a cooling fan, means for flowing air through the cooling vent, means for outputting the air flow through a plurality of cooling holes on the top of the first electronic device. The present invention further provides for a second electronic device having a plurality of heat sink fins on the bottom. The bottom of the second electronic device coupled to the top of said first electronic device, means for aligning the plurality of cooling holes under the plurality of heat sink fins, and means for outputting the air through an output of the heat sink fins.


REFERENCES:
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patent: 6297958 (2001-10-01), Lutz, Jr.
patent: 6522540 (2003-02-01), Sakaiya et al.

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