Electricity: conductors and insulators – Boxes and housings
Reexamination Certificate
2003-02-25
2004-05-25
Reichard, Dean (Department: 2831)
Electricity: conductors and insulators
Boxes and housings
C174S0170CT, C174S068300, C277S641000, C439S076100
Reexamination Certificate
active
06740809
ABSTRACT:
FIELD OF THE INVENTION
The present invention relates to enclosures for housing electronic components and other sensitive equipment.
BACKGROUND OF THE INVENTION
In order to protect electronic components from the adverse affects of ambient environmental conditions, such components are often housed within enclosures that are environmentally sealed to prevent moisture and other corrosive or otherwise debilitating gases and liquids located outside the enclosure from reaching the components inside.
FIG. 1A
shows an exploded perspective view of an exemplary, conventional enclosure
100
for housing electronic components. As shown in
FIG. 1A
, enclosure
100
contains a cover
102
, a chassis
104
, and a face plate
106
. Electronic components (not shown) such as printed wire boards and individual electronic modules are mounted within or on chassis
104
. Cover
102
is then mounted to chassis
104
to form a partial assembly that encloses the electronic components on five of the six sides of enclosure
100
(i.e., the top, bottom, left, right, and back sides). The remaining, front side of enclosure
100
is formed by mounting face plate
106
onto the front side of the partial assembly formed by chassis
104
and cover
102
. Face plate
106
has apertures
108
that provide electrical access to the electronic components housed in enclosure
100
.
FIG. 1B
shows a detail of one corner of cover
102
of enclosure
100
,
FIG. 2A
shows a top view of cover
102
, and
FIG. 2B
shows a top view of the corner shown in FIG.
1
B. As shown in the
FIGS. 1-2
, cover
102
has a generally U-shaped groove
110
running around the periphery of the top side of cover
102
along the left, right, and back sides of cover
102
. Groove
110
is adapted to retain a deformable (e.g., silicone rubber or polymer) gasket (not shown) that runs along the entire length of groove
110
. In particular, groove
110
is specifically designed such that the gasket will extend above the top surface of cover
102
along the entire length of groove
110
. As such, when cover
102
is mounted to chassis
104
, the gasket will be compressed by the mating surfaces of those parts to form a sufficiently tight seal between cover
102
and chassis
104
along the left, right, and back sides of the resulting partial assembly referred to herein as the chassis/cover sub-assembly. Moreover, the width of the groove is preferably slightly undersized compared to the size (e.g., width or diameter) of the gasket to provide a friction fit for the gasket.
Furthermore, it is desirable for the ends of the gasket to protrude beyond the front side of the chassis/cover sub-assembly at both ends of groove
110
to form a portion of the sealing configuration when face plate
106
is mounted onto the front side of the sub-assembly.
Ideally, during assembly of an enclosure, such as enclosure
100
of
FIGS. 1-2
, the gasket is inserted into the groove using only vertical force, making sure that the gasket extends beyond the front side of the cover on both ends of the groove. The ends of the gasket are then trimmed as necessary to achieve a desired amount of protrusion. The cover is then mounted over the chassis to form the chassis/cover subassembly, followed by the mounting of the face plate onto the front side of the chassis/cover subassembly.
In practice, however, an assembler might insert the gasket within the groove by applying both vertical and lateral pressure to the gasket, e.g., using a finger or thumb, from one end of the groove around the periphery of the cover to the other end of the groove. As such, assemblers tend to stretch the gaskets as they are inserted into the grooves, thereby creating strain in the gaskets. After the ends of a gasket are trimmed, the strain on the gasket may overcome the friction fit, causing the gasket to relieve itself (i.e., contract along its length). As a result, one or both ends of the gasket may pull back into the groove, thereby eliminating one or both of the desirable, front-side protrusions at the ends of the groove. The subsequent application of the chassis and face plate may then fail to appropriately seal the assembly. In particular, the resulting “gaps” in the enclosure can cause leakage failure for UL testing or other quality issues for the electronic components.
REFERENCES:
patent: 3643968 (1972-02-01), Horvath
patent: 4192520 (1980-03-01), Hasegawa
patent: 4298204 (1981-11-01), Jinkins
patent: 4669432 (1987-06-01), Harada
patent: 5536023 (1996-07-01), Surbrook et al.
patent: 5550324 (1996-08-01), Black et al.
patent: 5700977 (1997-12-01), Ford et al.
patent: 6309257 (2001-10-01), Huang
patent: 6492590 (2002-12-01), Cheng
patent: 6577504 (2003-06-01), Lofland et al.
Andrew Corporation
Estrada Angel R.
Mendelsohn Steve
Reichard Dean
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