Electricity: electrical systems and devices – Housing or mounting assemblies with diverse electrical... – For electronic systems and devices
Reexamination Certificate
2000-09-07
2001-08-21
Picard, Leo P. (Department: 2835)
Electricity: electrical systems and devices
Housing or mounting assemblies with diverse electrical...
For electronic systems and devices
C361S735000, C165S080400, C062S259200
Reexamination Certificate
active
06278611
ABSTRACT:
BACKGROUND OF THE INVENTION
1. Field of the Invention
This invention relates generally to a rack for mounting and connecting a plurality of electronics modules and, more particularly, to a rack for mounting and connecting a plurality of electronics modules, where the rack does not include inlet and outlet cooling plenums.
2. Discussion of the Related Art
Many electronic systems employ independent electronics modules that are slidably positioned within an electronics rack, and electrically connected to each other therein. One particular known electronics rack is used for mounting and connecting avionics electronics modules. As is well understood in the art, the operation of electronics systems generates heat. The closer the electronics modules are mounted together, the more heat is generated per unit area, and the harder it is for the heat to dissipate. If too much heat is generated, the electronics modules may not operate correctly, and their useful life will be reduced. Additionally, generation of a significant amount of heat creates a fire hazard. Therefore, one of the primary functions of the rack is to provide cooling of the modules.
In one rack design, cooling air is forced through a heat exchanger configured within the rack to provide cooling of the electronic modules.
FIG. 1
is a perspective view of an electronics rack
10
of this type that is known in the art. The rack
10
includes an outer housing
12
having a front opening
14
. A lower card guide
16
is mounted at a lower location within the housing
12
by flanges
18
secured to opposing side panels
20
and
22
of the housing
12
. The card guide
16
is a single piece unit made of a heat conductive metal, such as aluminum. The card guide
16
includes a plurality of parallel tabs
28
extending from front to back that define grooves
30
therebetween. Each tab
28
includes an alignment nub
32
positioned proximate the opening
14
. An upper card guide (not shown) is also mounted within the housing
12
at an upper location in the same manner, and also includes parallel tabs defining grooves therebetween.
The parallel grooves
30
in the lower card guide
16
and the parallel grooves in the upper card guide are aligned and suitably spaced apart to receive electronics modules
36
in a certain configuration. Each electronics module
36
includes a lower tab
38
that is inserted in one of the grooves
30
in the lower guide
16
and an upper tab
40
that is inserted in a corresponding groove in the upper guide. When the module
36
is slid into the housing
12
, an electrical connector
42
is electrically connected with a mating electrical connector (not shown) at the back of the housing
12
to provide the desired electrical connection. Multiple electronics modules
36
are slid into the housing
12
in a parallel format to provide the overall electrical system. It is generally desirable to set the spacing of the grooves
30
and the thicknesses of the electronics modules
36
to allow as many modules
36
as possible to be stored in the rack
10
to conserve space.
The modules
36
generate heat during operation. The rack
10
therefore provides assisted cooling of the modules
36
to draw away the heat.
FIG. 2
is a cross-sectional view of the rack
10
through line
2
—
2
in FIG.
1
. The tabs
38
and
40
make contact with the lower card guide
16
and the upper card guide in a heat transfer engagement. To provide the cooling, forced air is caused to circulate across the lower card guide
16
and the upper card guide to draw heat away from the modules
36
. An inlet plenum
46
is attached to the side surface
20
at one side of the housing
12
and an outlet plenum
48
is attached to the side surface
22
at an opposite side of the housing
12
. Of course, the inlet and outlet plenums
46
and
48
can be reversed. The inlet plenum
46
includes a rectangular opening
50
through a backwall
52
of the housing
12
that allows cooling air to enter the plenum
46
. The outlet plenum
48
includes a rectangular opening
54
through the wall
52
that allows the heated air to exit the outlet plenum
48
and the housing
12
.
A heat exchanger
60
is positioned within a specially configured cavity in a base plate
62
between a bottom wall of the housing
12
and the card guide
16
. A similar heat exchanger is also provided between the top wall and the upper card guide. The heat exchanger
60
includes a plurality of spaced apart fins
64
that extend transverse to the opening
14
. The cooling air from the inlet plenum
46
is forced into the heat exchanger
60
and flows between the fins
64
across the card guide
16
to collect heat therein. The fins
64
increase the surface area exposed to the cooling air to increase the heat removal capacity. As the operation of the modules
36
heats the upper and lower card guides, air flowing between the fins
64
acts to draw heat away from the modules
36
, providing the cooling. The inlet plenum
46
provides cooling air to both the upper and lower heat exchangers.
The spacing between the cooling fins
64
, and the height and width of the cooling fins
64
, is determined by the desired amount of air flow to provide the desired amount of cooling, as is understood in the art. In alternate varations, the rack
10
can include a plurality of stack layers where electronics modules
36
are positioned between card guides in each separate layer, and cooling is provided at each layer in the manner as discussed herein.
The above-described process of providing cooling of electronics module in an electronics rack has been effective in removing heat from the electronics module. However, the overall electronics packaging density of the system is reduced because finite amounts of volume must be dedicated to the inlet and outlet plenums
46
and
48
. Because the size and weight of the electronic system may be an important parameter in different types of systems, it may be desirable to provide an electronics rack that eliminates the plenums
46
and
48
, but distributes cooling air to the modules
36
at a higher or at least as high volumetric efficiency. It is therefore an object of the present invention to provide such a plenumless electronics rack.
SUMMARY OF THE INVENTION
In accordance with the teachings of the present invention, a rack for a plurality of electronics modules is disclosed where the rack does not include air cooling plenums to conserve space. However, it is still desirable to apply and remove cooling air through a back wall of the rack. Therefore, because the air cooling plenums have been eliminated, a different technique must be provided to allow air to flow through the heat exchanger transverse to the front opening in the rack.
To provide this technique, the present invention proposes a heat exchanger including three separate sections. Each section includes a plurality of spaced-apart parallel fins. First and second end sections of the heat exchanger include cooling fins that extend parallel to each other in a front-to-back direction relative to the direction the modules are slid into the rack. The first and second end sections are positioned at opposite ends of a center section, where the fins of the center section extend in a direction transverse to the direction the modules are slid into the rack and perpendicular to the fins in the first and second sections. The channels between the fins in the first and second end sections are aligned with inlet and outlet ports in a back panel of the rack. The first and second end sections are angled relative to ends of the center section so that the fins between the sections are aligned. Cooling air that enters the first section from the air inlet port flows through the first end section, then down the center section and into the second end section, and then out the air outlet port.
Additional objects, features and advantages of the invention will become apparent from a consideration of the following description and the appended claims when taken in connection with the accompanying drawings.
REFERENC
Arena John J.
Matonis Richard A.
Smith David M.
Datskovsky Michael
Keller Robert W.
Picard Leo P.
TRW Inc.
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