Electricity: electrical systems and devices – Housing or mounting assemblies with diverse electrical... – For electronic systems and devices
Reexamination Certificate
1999-01-22
2001-01-23
Picard, Leo P. (Department: 2835)
Electricity: electrical systems and devices
Housing or mounting assemblies with diverse electrical...
For electronic systems and devices
C361S698000, C361S700000, C174S015200, C165S080400, C165S104330
Reexamination Certificate
active
06178088
ABSTRACT:
CROSS-REFERENCE TO RELATED APPLICATION
This application claims priority of European Patent Application No. 98300550.5, which was filed on Jan. 27, 1998.
FIELD OF THE INVENTION
This invention relates to electronic apparatus contained in a heat dissipative external enclosure.
BACKGROUND OF THE INVENTION
In the absence of forced convection, an electronic apparatus will be hotter at the top of its external enclosure than at the bottom. The situation is worse for apparatus sealed for use outside where internally generated heat has to be dissipated by the external enclosure. Ideally components which generate large amounts of heat would be sited lower in the external enclosure than components which generate less heat. However, that is not always possible.
Heat pipes have been used to conduct heat away from components to cooler positions in the external enclosure. Conventionally, the evaporator of a heat pipe is in direct thermal contact with a power component e.g. by clamping or bonding. The condenser of the heat pipe is conventionally pressed into a groove in the wall of the external enclosure, being an interference fit in the groove so as to ensure good thermal contact. The heat pipe has a round cross section and the groove has a corresponding round bottom. The step of pressing the heat pipe into the groove may also be used to distort the pipe so that it finishes flush with the top of the groove.
A problem with this is that removal of the heat pipe is virtually impossible which makes removal of the circuit board on which the component is mounted very difficult.
In some external enclosures individual units have to be isolated from one another against radio frequency (RF) interference by closed internal housings. Another problem with using the heat pipe as described above is that it would be difficult to maintain the RF isolation around a heat pipe that would have to enter the internal housing.
SUMMARY OF THE INVENTION
The invention solves the above problems by providing an electronic apparatus having a heat pipe that is thermally bonded to plates to internal and external enclosures. The electronic apparatus is located in a heat dissipative external enclosure. The electronic apparatus having at least one unit contained in a thermally conductive internal housing providing RF isolation and mounted on a wall of the external enclosure in thermal contact therewith. The electronic apparatus also having a heat pipe having a first plate bonded to its evaporator and a second plate bonded to its condenser, both bonds being thermally conductive. The first plate being mounted by fixings in thermal contact with the internal housing, the second plate being mounted by fixings in thermal contact with the wall of the external enclosure at a position lower, in use, than the first plate. This allows the heat pipe to be easily removed. This also allows the inner housing to maintain RF isolation.
For best effect, the first plate is preferably located adjacent one or more power components inside the internal housing. The first plate is preferably mounted in a recess in the internal housing.
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European Search Report dated Jul. 2, 1998.
Chervinsky Boris L.
Lucent Technologies - Inc.
Picard Leo P.
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