U.S. patent application number 14/319619 was filed with the patent office on 2015-12-31 for angled card cage for improved cooling airflow in front to back airflow products.
The applicant listed for this patent is Alcatel-Lucent Canada. Inc., Alcatel Lucent USA, Inc.. Invention is credited to Stefano De Cecco, Joseph D. Griffin, Peter J. Serjak.
Application Number | 20150382510 14/319619 |
Document ID | / |
Family ID | 54932165 |
Filed Date | 2015-12-31 |
United States Patent
Application |
20150382510 |
Kind Code |
A1 |
Serjak; Peter J. ; et
al. |
December 31, 2015 |
ANGLED CARD CAGE FOR IMPROVED COOLING AIRFLOW IN FRONT TO BACK
AIRFLOW PRODUCTS
Abstract
An angled card cage for improved cooling airflow in front to
back airflow products is disclosed. The angled card cage for
improved cooling airflow includes a card cage having horizontally
mounted circuit cards wherein the card cage is oriented at a
non-orthogonal yaw angle relative to the front facing of an
equipment rack. The angled card cage for improved cooling airflow
provides advantages over systems known in the art by reducing
pressure head losses incurred by the cooling air stream.
Inventors: |
Serjak; Peter J.;
(Stittsville, CA) ; Griffin; Joseph D.; (Lake
Oswego, OR) ; Cecco; Stefano De; (Ottawa,
CA) |
|
Applicant: |
Name |
City |
State |
Country |
Type |
Alcatel Lucent USA, Inc.
Alcatel-Lucent Canada. Inc. |
Murray Hill
Ottawa |
NJ |
US
CA |
|
|
Family ID: |
54932165 |
Appl. No.: |
14/319619 |
Filed: |
June 30, 2014 |
Current U.S.
Class: |
174/541 |
Current CPC
Class: |
H05K 7/20581 20130101;
H05K 7/20572 20130101 |
International
Class: |
H05K 7/20 20060101
H05K007/20 |
Claims
1. An electronics enclosure for mounting on an equipment rack
having a front and back orientation in use, the electronics
enclosure comprising: a first front face oriented in the direction
of the front of said equipment rack, said first front face
including at least one air inlet; a second back face oriented in
the direction of the back of said equipment rack, said second back
face including at least one air exhaust; a card cage having a
plurality of horizontal card slots vertically offset from one
another for receiving a plurality of electric cards, wherein each
of the plurality of card slots have respective longitudinal axes
that are substantially parallel; said card cage oriented at a
non-orthogonal yaw angle with respect to said first front face; a
first plenum disposed operatively between said air inlet and the
card cage; said first plenum having a cross-section which becomes
smaller as the distance increases from said air inlet; a second
plenum disposed operatively between the card cage and said air
exhaust, the second plenum having a cross-section which becomes
larger as the distance decreases towards said air exhaust; and at
least one fan operative to force air to flow along an airflow
pathway that extends from said air inlet into said first plenum,
through said card cage, into said second plenum, and out said air
exhaust.
2. An electronics enclosure as claimed in claim 1 wherein the yaw
angle is between 1.degree. and 25.degree..
3. An electronics enclosure as claimed in claim 2 wherein the yaw
angle is between approximately 5.degree. and approximately
10.degree..
4. An electronics enclosure as claimed in claim 3 wherein the yaw
angle is approximately 8.degree..
5. An electronics enclosure as claimed in claim 1 wherein said at
least one fan is disposed between said first plenum and said card
cage.
6. An electronics enclosure as claimed in claim 1 wherein said at
least one fan is disposed between said card cage and said second
plenum.
7. An electronics enclosure as claimed in claim 1 wherein said at
least one fan is disposed between said first plenum and said card
cage; and further comprising at least a second fan disposed between
said card cage and said second plenum.
Description
FIELD OF THE INVENTION
[0001] The invention relates to cooling air flow in equipment and
is particularly concerned improving cooling performance by
minimizing cooling air pressure head loss in rack mounted equipment
shelves.
BACKGROUND OF THE INVENTION
[0002] It is common in telecommunications systems to rely on card
cages that are secured in standardized racking systems.
Pre-determined specifications define the height and other
dimensions of the enclosures for these card cages so that equipment
provided by various manufacturers may be readily used in
combination in standard racks. Some example standards for
dimensioning include, but are not limited to, AMC, ARINC, ATCA,
cPCI, MicroTCA, VME, and VME 64. These standards are defined by
various industry standards organizations including ANSI, IEEE,
PICMG, VITA, as well as others including military organizations. A
the electronics cards that are mounted in the card cages generate
heat during their operation, appropriate amounts of cooling airflow
are provided to carry the heat away from the operating
equipment.
[0003] North American data centers and telecommunication companies
are increasingly demanding that central office equipment
incorporate front to back cooling solutions, wherein cooling air is
drawn in from the front of the cabinet and exhausted to the rear.
This allows the service provider to set up more manageable HVAC
(Heating, Ventilating, and Air Conditioning) environments with
cooler (front) maintenance aisles and warmer (rear) wiring
aisles.
[0004] This requirement causes implementation challenges with
smaller sized products and enclosures that are typically designed
with horizontal cards using side-to-side cooling. Front to back air
cooled systems require significantly more rack height, due to
larger cooling intake and exhaust requirements and typically
require cards to be installed vertically or limit the thermal load
of horizontal cards.
[0005] Referring to FIG. 1, there may be seen a typical Central
Office Small Box card cage assembly 100 has rack mounting flanges
102 according to the prior art. Circuit cards 104 are mounted
within card cage assembly 100. Fans 106 induce cooling air flow to
pass through card cage assembly 100 and circuit cards 104, with the
cooling air entering on the fan side of card cage assembly 100 and
exiting the opposite side.
[0006] Referring to FIG. 2, there may be seen an alternate solution
according to the prior art, wherein front to back airflow is
achieved at the expense of additional vertical rack space. Card
cage assembly 200 has been rotated by 90 degrees from the
orientation shown in FIG. 1, and again has circuit cards 204
mounted within card cage assembly 200 and fans 206. Large intake
baffles 208 are located at the bottom of the card cage assembly
200, and corresponding large exhaust baffles 210 are located at the
top of the chassis. Cooling air flow enters at the front of card
cage assembly 200 through intake baffles 208, is accelerated by
fans 206, and proceeds vertically through card cage assembly 200,
passing circuit cards 204 and cooling them thereby. The heated air
exits exhaust baffles 210 at the top of the card cage assembly 200
and is directed to the rear of the rack. By way of example, in FIG.
2 the 10.5'' tall Small Box card cage assembly 200 in this
configuration requires approx. 26.3'' of rack height to provide
sufficient intake and exhaust openings. In space constrained
central offices this additional vertical height requirement is not
a preferred arrangement from the operator's perspective.
[0007] Referring now to FIGS. 3A and 3B, there may be seen yet
another prior art method of routing cooling air through a card cage
assembly. FIG. 3A provides an elevation view of this configuration
from the front of the equipment rack. Central Office Small Box card
cage assembly 300 has rack mounting flanges 302 according to the
prior art. Circuit cards 304 are mounted within card cage assembly
300. Fans 306 induce cooling air flow to pass through card cage
assembly 300 and circuit cards 304, with the cooling air entering
opposite to the fan side of card cage assembly 300 at 308 and exits
after passing through the fan assembly 306 at exhaust 310. FIG. 3B
is a view of this configuration from the top. Cooling air enters
from the front at 308, passes through the equipment cards 304,
passes through the fan assembly 306, and exits via the rear exhaust
310. In this configuration cooling air must navigate several sharp
turns--as it enters the intake baffles and then turns 90.degree. to
flow through the cards 304, and then upon exiting the fan assembly
306 it then turns a further 90.degree. to flow through the rear
exhaust 310. These changes in air direction result in pressure head
loss, limiting the amount of cooling air that is provided by the
system fans.
[0008] Therefore, there exists a need to overcome the drawbacks
associated with the prior art as discussed above.
SUMMARY OF THE INVENTION
[0009] It is an object of the invention to provide a construction
which reduces pressure losses in cooling air flows when routed
through the front of an equipment assembly to exhaust in the back
of the equipment assembly.
[0010] According to a first aspect of the invention there is
disclosed an electronics enclosure for mounting on an equipment
rack having a front and back orientation in use, the electronics
enclosure having a first front face oriented in the direction of
the front of the equipment rack, the first front face including at
least one air inlet; a second back face oriented in the direction
of the back of the equipment rack, the second back face including
at least one air exhaust; a card cage having a plurality of
horizontal card slots vertically offset from one another for
receiving a plurality of electric cards, wherein each of the
plurality of card slots have respective longitudinal axes that are
substantially parallel; the card cage oriented at a non-orthogonal
yaw angle with respect to the first front face; a first plenum
disposed operatively between the air inlet and the card cage; the
first plenum having a cross-section which becomes smaller as the
distance increases from the air inlet; a second plenum disposed
operatively between the card cage and the air exhaust, the second
plenum having a cross-section which becomes larger as the distance
decreases towards the air exhaust; and at least one fan operative
to force air to flow along an airflow pathway that extends from the
air inlet into the first plenum, through the card cage, into the
second plenum, and out the air exhaust.
[0011] In some embodiments of this aspect of the invention the yaw
angle is between 1.degree. and 25.degree.. In some of these
embodiments the yaw angle is between approximately 5.degree. and
approximately 10.degree.. In others of these embodiments the yaw
angle is approximately 8.degree..
[0012] In some embodiments of the invention the at least one fan is
disposed between the first plenum and the card cage. In other
embodiments of the invention the at least one fan is disposed
between the card cage and the second plenum. In yet other
embodiments of the invention the at least one fan is disposed
between the first plenum and the card cage; and there is at least a
second fan disposed between the card cage and the second
plenum.
[0013] Note: in the following the description and drawings merely
illustrate the principles of the invention. It will thus be
appreciated that those skilled in the art will be able to devise
various arrangements that, although not explicitly described or
shown herein, embody the principles of the invention and are
included within its spirit and scope. Furthermore, all examples
recited herein are principally intended expressly to be only for
pedagogical purposes to aid the reader in understanding the
principles of the invention and the concepts contributed by the
inventor(s) to furthering the art, and are to be construed as being
without limitation to such specifically recited examples and
conditions. Moreover, all statements herein reciting principles,
aspects, and embodiments of the invention, as well as specific
examples thereof, are intended to encompass equivalents
thereof.
BRIEF DESCRIPTION OF THE DRAWINGS
[0014] The present invention will be further understood from the
following detailed description of embodiments of the invention,
with reference to the drawings in which like reference numbers are
used to represent like elements, and:
[0015] FIG. 1 illustrates an exemplary rack mounted card cage
assembly according to the prior art having cooling air ported into
one side and exiting from the other side of the rack;
[0016] FIG. 2 illustrates an exemplary rack mounted card cage
assembly according to the prior art having cooling air ported into
the bottom and exiting from the top side of the card cage
assembly;
[0017] FIGS. 3A and 3B illustrates an exemplary rack mounted card
cage assembly according to the prior art having cooling air ported
into the front, passing across the assembly and exiting from the
back side of the card cage assembly;
[0018] FIG. 4 illustrates a plan view of an exemplary rack mounted
card cage assembly according to an embodiment of the invention
having cooling air ported into the front and exiting from the back
side of the card cage assembly;
[0019] FIG. 5 illustrates an isometric elevation view of the
exemplary rack mounted card cage assembly of FIG. 4; and
[0020] FIG. 6 illustrates a plan view of an exemplary rack mounted
card cage assembly according to an embodiment of the invention
illustrating the bend radius of cables connected to the front of
the assembly.
DETAILED DESCRIPTION
[0021] In the following description, numerous specific details are
set forth. However, it is understood that embodiments of the
invention may be practiced without these specific details. In other
instances, well-known assemblies, structures and techniques have
not been shown in detail in order not to obscure the understanding
of this description. It will be appreciated, however, by one
skilled in the art that the invention may be practiced without such
specific details. Those of ordinary skill in the art, with the
included descriptions, will be able to implement appropriate
functionality without undue experimentation.
[0022] References in the specification to "one embodiment", "an
embodiment", "an example embodiment", etc., indicate that the
embodiment described may include a particular feature, structure,
or characteristic, but every embodiment may not necessarily include
the particular feature, structure, or characteristic. Moreover,
such phrases are not necessarily referring to the same embodiment.
Further, when a particular feature, structure, or characteristic is
described in connection with an embodiment, it is submitted that it
is within the knowledge of one skilled in the art to effect such a
feature, structure, or characteristic in connection with other
embodiments whether or not explicitly described.
[0023] In the following description and claims, the terms "coupled"
and "connected," along with their derivatives, may be used. It
should be understood that these terms are not intended as synonyms
for each other. "Coupled" is used to indicate that two or more
elements, which may or may not be in direct physical or electrical
contact with each other, cooperate or interact with each other.
"Connected" is used to indicate the establishment of communication
between two or more elements that are coupled with each other.
[0024] In general in the description of the figures, like reference
numbers are used to represent like elements.
[0025] Referring now to FIG. 4 there may be seen a plan view of an
exemplary rack mounted card cage assembly according to an
embodiment of the invention having cooling air ported into the
front and exiting from the back side of the card cage assembly.
Card cage assembly 400, fans 406, and associated baffles 408 and
410 have flanges 402 for attachment to an equipment rack. Card cage
assembly 400 and fans 402 are oriented on a non-orthogonal yaw
angle with respect to the front of the equipment rack as
established by flanges 402. With the card cage 400 and fan assembly
406 angled as shown, the intake opening into baffle 408 and exhaust
opening at baffle 410 in the chassis obtain less impedance to air
flow due to the wedge-shape openings. The cooling air is turned
less, thereby minimizing the pressure head loss as cooling air
traverses the assembly. Less pressure head loss results in greater
cooling effectiveness.
[0026] Thermal simulations have shown that with horizontal cards
mounted in a card cage assembly angled by 8.degree. relative to the
chassis side walls, the result obtained would be a 28% air
flow-rate increase, relative to a non-angled card cage and a worst
case fan operating back-pressure reduction of 10%. Subsequent
thermal testing on prototype units has confirmed the results
indicated by the thermal simulation. The present invention
contemplates that the yaw angle at which the card cage assembly is
displaced back from the front face established by the rack is
between 1.degree. and 25.degree., with values of 5.degree. to
approximately 10.degree. being appropriate and advantageous for
most applications.
[0027] Referring now to FIG. 5, there may be seen an isometric
elevation view of the exemplary rack mounted card cage assembly of
FIG. 4. Card cage assembly 500, intake duct 508, and output duct
510 have mounting flanges 502 for anchoring the assembly to a rack
(not shown). Cooling air flows in intake duct 508, traverses the
horizontally mounted cards 504 in card cage assembly 500, pass
through fans 506 (behind panel) and exit through exhaust duct 510.
Note that the circuit board cards mounted in card cage assembly 500
are mounted in the horizontal position. This horizontal
orientation, as opposed to the more normal vertical orientation, is
a requisite part of the cooling assembly in order to allow the
cooling air to traverse the assembly. Vertically mounted circuit
boards would block the cooling air flow from passing from the
intake side to the exhaust side.
[0028] Referring now to FIG. 6, there is shown a plan view of an
exemplary rack mounted card cage assembly according to an
embodiment of the invention. Mounting flanges 602, intake plenum
608 and exhaust plenum 610 are all indicated. As well, reference
line 601 highlights a further advantage of embodiments of the
invention with respect to the bend radius of cables connecting to
circuit cards mounted in the card cage assembly. As a portion of
the front of the card cage assembly is oriented back from the plane
of the rack, a greater bending radius area is established for the
cables connecting to the circuit cards. This greater bend radius
may be effected without as much obtrusion into the equipment
corridor in front of the racks, an advantage both to working in the
proximity of the equipment and an advantage with respect to
improving the mechanical reliability of optical and electrical
cabling at the connectors.
[0029] Accordingly what has been disclosed is a method and
apparatus for enhancing the flow of cooling air through an
electronics assembly.
[0030] Numerous modifications, variations and adaptations may be
made to the embodiment of the invention described above without
departing from the scope of the invention, which is defined in the
claims.
* * * * *