U.S. patent application number 13/126291 was filed with the patent office on 2011-08-25 for equipment case.
This patent application is currently assigned to BAE SYSTEMS PLC. Invention is credited to Adrian Thomas Rowe.
Application Number | 20110203770 13/126291 |
Document ID | / |
Family ID | 42128310 |
Filed Date | 2011-08-25 |
United States Patent
Application |
20110203770 |
Kind Code |
A1 |
Rowe; Adrian Thomas |
August 25, 2011 |
EQUIPMENT CASE
Abstract
An equipment case is provided. The case comprises a sealed
housing unit configured to receive an item of equipment. Cooling
means, associated with the housing unit, are provided for
maintaining an operational thermal environment within the equipment
case.
Inventors: |
Rowe; Adrian Thomas; (Isle
of Wright, GB) |
Assignee: |
BAE SYSTEMS PLC
London
GB
|
Family ID: |
42128310 |
Appl. No.: |
13/126291 |
Filed: |
October 27, 2009 |
PCT Filed: |
October 27, 2009 |
PCT NO: |
PCT/GB2009/051443 |
371 Date: |
April 27, 2011 |
Current U.S.
Class: |
165/80.1 |
Current CPC
Class: |
H05K 7/202 20130101 |
Class at
Publication: |
165/80.1 |
International
Class: |
F28F 7/00 20060101
F28F007/00 |
Foreign Application Data
Date |
Code |
Application Number |
Oct 27, 2008 |
EP |
08253484.3 |
Oct 27, 2008 |
GB |
0819692.5 |
Claims
1. A field equipment case comprising: a sealed housing unit
configured to receive an item of equipment; and cooling system
associated with the housing unit for maintaining an operational
thermal environment within the equipment case.
2. A case according to claim 1, wherein the cooling system is
directly connected to the housing unit.
3. A case according to claim 1, wherein the cooling system is
spaced from the housing unit but in fluid communication
therewith.
4. A case according to claim 1 or claim 2, wherein the cooling
system comprises a first fan, mounted within the housing unit, and
a second fan, mounted external to the housing unit.
5. A case according to claim 4, wherein the first fan is an axial
fan.
6. A case according to claim 4, wherein the second fan is a
centrifugal fan.
7. A case according to claim 1 or claim 2, wherein the cooling
system comprises a forced flow heat exchanger.
8. A case according to claim 1 or claim 2, wherein the cooling
system is configured to establish a counter current thermal
exchange mechanism between a fluid internal to the housing unit and
a fluid external to the housing unit.
9. (canceled)
Description
[0001] The present invention relates to the field of equipment
cases, in particular, to controlling the environment within such an
equipment case.
[0002] A conventional equipment case, housing and thereby
protecting equipment such as a battlefield communications system,
comprises a box having openings therein through which air can pass.
Thus convection within the box is enhanced and cooling of the
equipment is effected. Filters are placed in the openings to
prevent (or at least inhibit) ingress of dust and/or fluid
therethrough.
[0003] Such filters perform reasonably well when initially
installed, permitting minimal levels of dust ingress, however they
soon become clogged so that air flow therethrough is inhibited.
Consequently, the filters need to be frequently maintained and
cleaned or replaced at intervals if the thermal conditions within
the equipment case are not to deteriorate rapidly such that
overheating becomes a problem.
[0004] Even a small level of dust ingress serves to contaminate the
equipment housed within the case. Such contamination is detrimental
to the performance and service life of the equipment.
[0005] It is desirable to provide an equipment case having a
reduced maintenance requirement, whilst maintaining or enhancing
the level of protection for equipment contained therein.
[0006] According to a first aspect, the present invention provides
a field equipment case comprising: [0007] a sealed housing unit
configured to receive an item of equipment; and [0008] cooling
means associated with the housing unit for maintaining an
operational thermal environment within the equipment case.
[0009] By providing a sealed housing unit, ingress of moisture and
particulate matter is inhibited. Consequently, deterioration in the
performance and service life of the item of equipment housed within
the equipment case is minimised.
[0010] The cooling system may be directly connected to the housing
unit or it may be spaced from the housing unit but in fluid
communication therewith.
[0011] The cooling system may comprise a first fan, mounted within
the housing unit, and a second fan, mounted external to the housing
unit. The first fan may be an axial fan. The second fan may be a
centrifugal fan.
[0012] The cooling system may comprise a forced flow heat exchanger
and it may be configured to establish a counter current thermal
exchange mechanism between an internal fluid and an external
fluid.
[0013] The present invention will now be described in more detail,
by way of example only, in reference to the accompanying drawings
in which:
[0014] FIG. 1 illustrates an equipment case;
[0015] FIG. 2 represents a cross section of FIG. 1 on X-X,
illustrating a cooling system;
[0016] FIG. 3 illustrates a part of the cooling system internal to
the equipment case;
[0017] FIG. 4 illustrates a part of the cooling system external to
the equipment case;
[0018] FIG. 5 illustrates a comparison between a parallel flow and
a counter flow thermal transfer system; and
[0019] FIG. 6 illustrates a cross section, similar to that shown in
FIG. 2, of an alternative equipment case.
[0020] FIG. 1 illustrates an equipment case 10. The dimensions of
the case 10 are selected to accommodate a chosen type and model of
equipment within the envelope described thereby. A housing unit 20
of the equipment case 10 defines a sealed cavity 25 for
accommodating electronic equipment (not shown). Such an arrangement
serves to inhibit the ingress of fluid and dust or other
particulate matter into the equipment case 10 which could,
potentially, damage the equipment protected thereby.
[0021] In one embodiment, the case is sealed to the extent that it
is considered to be dust and weather proof to an IP rating of 65.
In other words the unit is "totally protected from dust" and
"protected from low pressure jets of water from all
directions".
[0022] As a consequence, when used in hot environments (say in
excess of 40.degree. C.) the internal thermal conditions of the
equipment case 10 may be elevated. Equipment contained within the
case 10 also, generally, generates heat and further contributes to
the elevation of the internal temperatures.
[0023] By sealing the housing unit 20 a closed air loop is
established, convection being the dominant mechanism of heat
transfer used to cool the equipment.
[0024] Typically, electronic equipment contained in the case 10
ought not to exceed a threshold operating temperature of, say,
50.degree. C. Thus it may be necessary to maintain a temperature
difference of only 10.degree. C. between the environment internal
to the equipment case 10 and the environment external to the
equipment case 10.
[0025] The equipment case 10 is designed to minimise transmission
of shock and vibrations experienced by the case 10 to equipment
accommodated therewithin. For example, the equipment may be mounted
within a frame, whereby the frame itself is connected to the
housing unit 20 via shock suppression mounting brackets. Conduction
of heat from the equipment to the housing unit 20 is, consequently
minimal.
[0026] Electronic equipment installed within an equipment case 10
is, generally, both a source of and is susceptible to
electromagnetic interference (EMI). In order to inhibit detection
of the unit and to protect the unit from exposure to external
electromagnetic interference, it is desirable to augment the
electromagnetic shielding properties of the case 10. By eliminating
any openings from the housing unit 20, enhanced electromagnetic
shielding is achieved.
[0027] FIG. 2 illustrates a cross section of the equipment case
through line X-X such that a plan view of the case 10, as
illustrated in FIG. 1, is presented.
[0028] The equipment case 10 comprises a housing unit 20 coupled to
a cooling system 30. The cooling system 30 comprises a number of
components mounted on a wall 40 of the housing unit 20. An interior
surface 45 of wall 40, namely that located inside the housing unit
20 of equipment case 10, is illustrated in FIG. 3. An axial fan 50
is mounted on surface 45 together with a number of internal heat
sinks 55. In the current embodiment, two internal heat sinks 55 are
provided. The axial fan 50 is mounted centrally, between the two
internal heat sinks 55 and is configured to draw air through the
heat sinks 55 before redirecting the air stream into the cavity 25
of the equipment case 10.
[0029] Returning to FIG. 2, in combination with FIG. 4, an exterior
surface 60 of wall 40 is presented. External heat sinks 65 are
mounted on surface 60. The location of these external heat sinks 65
correspond to the internal heat sinks 55 mounted on internal
surface 45. Wall 40 comprises a thermally conductive material such
as a metal, to ensure that each external heat sink 65 is in thermal
communication with a respective heat sink 55 located across the
wall 40.
[0030] In this embodiment the wall 40 is made from aluminium, or an
aluminium alloy, however other metals comprising copper or
stainless steel may be used. Alternatively, the internal heat sinks
55 may achieve thermal communication with the corresponding
external heat sinks 65 by using heat pipes or by direct contact
with one another through an aperture formed in the wall 40. If the
housing 20 comprising the wall 40 is made from a material heaving
low thermal conductivity, e.g. carbon or glass fibre composite
materials, a thermally conductive insert may be used locally
between the internal and external heat sinks 55, 65 to provide a
low resistance thermal path therebetween.
[0031] A corresponding number of centrifugal fans 70 (in this
embodiment two) are also located on the exterior surface 60. Each
centrifugal fan 70 is oriented such that ambient air drawn from the
external environment is forced through the external heat sinks 65
as depicted in FIG. 2 by the dotted arrows. Thus an air to air heat
exchanger is provided. In an alternative embodiment, one or more
axial fans (not shown) could replace the centrifugal fans 70.
[0032] In operation, the airflow inside the housing unit 20 is
drawn across heat sink 55 from an outer portion thereof to an inner
portion thereof. In contrast, external to the housing unit 20
airflow is forced through heat sinks 65 from an interior portion
thereof to an exterior portion thereof. Consequently, a counter
current thermal exchange mechanism is established and heat transfer
therebetween is consequently very efficient. FIG. 5 illustrates the
heat transfer mechanism in more detail.
[0033] In FIG. 5a, a parallel system is shown whereby at one side
of the combined heat sink a very significant thermal difference is
illustrated (T.sub.I1'-T.sub.E1') however, at the other side of the
heat sink a very small thermal difference is achieved
(T.sub.I2'-T.sub.E2'). The coolest part of the interior T.sub.I2'
approaches the temperature of the hottest part of the exterior
T.sub.E2'.
[0034] In contrast, FIG. 5b illustrates the counter current thermal
exchange mechanism, whereby a more consistent thermal difference
and, therefore thermal gradient, is achieved across the extent of
the heat sinks 55, 65. In particular, the coolest part T.sub.I2 of
the internal side 45 may reduce below the temperature T.sub.E2 of
the hottest part of the external side 60. Consequently, a more
efficient and greater level of heat transfer can be achieved.
[0035] In the illustrated embodiment, the internal and external
heat sinks 55, 65 are located adjacent one another in direct
thermal communication. Alternatively, the heat sinks 55, 65 could
be spaced from one another and joined together using heat
pipes.
[0036] As the equipment case 10 is a portable item it is necessary
to achieve a lightweight configuration. Consequently, the heat
sinks 55, 65 comprise lightweight compact heat exchange surfaces
having a high surface area to volume ratio. Pin fins may be used as
illustrated however, straight fins or foil fins are also
appropriated and may be used. Alternatively, a metal, foam or other
conductive material having a sufficiently large surface area to
volume ratio could be used. A cover plate is provided over each
respective heat sink 55, 65 so that fluid drawn or forced through
the, or each, heat sink 55, 65 is constrained.
[0037] In an alternative embodiment, the equipment case 10' may
comprise a housing unit 20' spaced from a cooling system 30' but in
fluid and, therefore, thermal communication therewith. As depicted,
the cooling system 30' is spaced from the housing unit 20'
connected thereto via ducts 80. The cooling system 30' may be
located on any face of the housing unit 20' as may prove convenient
and the ducts 80 are configured accordingly.
[0038] In summary, thermally coupled internal and external forced
flow heat exchangers are provided, whereby integrated fans provide
forced convection cooling to internal equipment accommodated within
a housing unit of the equipment case 10. In providing a forced flow
heat exchange mechanism, the orientation of the equipment case
becomes inconsequential as the cooling mechanism is unaffected
thereby, unlike for natural convection. Additionally, the use of a
counter flow exchange mechanism enhances performance such that
operating conditions can be achieved for the electronic equipment
even in particularly demanding thermal environments exceeding
40.degree. C.
* * * * *