US20070171600A1

US20070171600A1 - Electronics enclosure with solar shield

Info

Publication number: US20070171600A1
Application number: US11/637,841
Authority: US
Inventors: Albert Pedoeem; Kriss Replogle
Original assignee: Fujitsu Network Communications Inc
Current assignee: Fujitsu Ltd
Priority date: 2005-12-13
Filing date: 2006-12-13
Publication date: 2007-07-26
Also published as: WO2007070515A3; US20070133618A1; US20070201487A1; US20070133424A1; WO2007070516A2; US20070171614A1; US20070133533A1; US7852880B2; US8289858B2; US7436660B2; US7876753B2; US20070201486A1; US8184625B2; US20070211763A1; US7664843B2; WO2007070515A2; US7990853B2

Abstract

An apparatus for shielding an electronics enclosure is disclosed. The apparatus includes an inner enclosure that houses electronic components. An outer enclosure surrounds the inner enclosure, and is separated from the inner enclosure by a gap. The outer enclosure preferably comprises plastic, and comprises a plurality of perforations uniformly distributed over its surface. The plurality of perforations allow air to flow into the gap between the outer enclosure and the inner enclosure. At the same time, the perforations are configured and dimensioned such that they substantially prevent sunlight from directly striking the surface of the inner enclosure. In this manner, the apparatus prevents overheating of the electronic components while minimizing the space taken up by the enclosure.

Description

CROSS-REFERENCE TO RELATED APPLICATIONS

The present invention claims priority to Provisional Patent Application Ser. No. 60/749,577, filed Dec. 13, 2005, the entirety of which is incorporated herein by reference.

FIELD OF THE INVENTION

The present invention relates to enclosures for electronic equipment. More specifically, the present invention relates to an enclosure for electronic equipment that effectively dissipates the internally generated heat of the electronic equipment.

BACKGROUND OF THE INVENTION

Over the past 50 years, electronic equipment has become more and more prevalent in the average person's everyday life. With the invention of the transistor, electronics have rapidly become more and more powerful and sophisticated. At the same time, advances in technology have allowed electronics to penetrate nearly every aspect of our everyday lives. The home is no exception.
Increasingly, electronic equipment has allowed us to communicate with one another, or to receive other types of media services such as television, telephone service, internet, and satellite service. To provide these services, media providers often run cables of varying types from remote locations to individual homes. The cables, of varying types, allow individuals to receive telephone, internet, and cable service.
Each individual home or unit has an interface, referred to as a Network Interface Device (NID), located outside that allows a home's internal wiring to communicate with the cables from the media providers. The interface typically includes electronic equipment and circuitry. The nature of electrical circuitry requires that it be protected from the outside environment in order to function properly. As such, different enclosures have been devised in order to protect this equipment from the elements, such as wind, water, dust, and heat.
Overheating of equipment due to solar radiation, and heat generated by the electrical equipment itself, is the source of significant problems. Electrical equipment that overheats can malfunction, which results in costly repairs. To avoid overheating, enclosures employ a wide variety of techniques in an attempt to maintain an ambient temperature within an enclosure. This problem is not as prevalent with indoor electrical enclosures, which are currently more widespread, because these enclosures do not need to be sealed and are not exposed to solar radiation.
Although the outdoor Network Interface Device (NID), the housing for the demarcation point, is a mature technology, the inclusion of heat-dissipating and environmentally sensitive electronics and opto-electronics in particular in outdoor NID-like applications is a relatively new application. Previous outdoor applications have addressed the cooling problem by packaging the electronics in an enclosure that is larger in surface area, and hence less desirable by the customer, than is otherwise necessary for the physical packaging of the electronics and associated hardware. Prior art enclosures have also been designed to limit air intake to the bottom surface of an enclosure, and air exhaust to the top of the enclosure.
A drawback of more compact enclosures currently available is that they result in operating conditions for the electronic devices that are hotter than desirable under worst case environmental conditions and will reduce the life and reliability of the system below desirable levels. Higher power applications typically employ expensive and power-hungry cooling fans.
A continuing need exists for a low cost electrical enclosure that is capable of efficiently cooling electronic equipment. Moreover, a continuing need also exists for an electrical enclosure that can shield sensitive electronic equipment from solar radiation.

SUMMARY OF THE INVENTION

The present invention comprises a method and apparatus for mounting and cooling electronic equipment in a low-cost, preferably plastic, environmentally protected enclosure that is protected from excessive solar heating by a ventilated shield. The solar shield intercepts the solar radiation and allows the ambient environment on its outside surfaces and near ambient conditions on its inside surface. The surface temperature of the environmentally protected enclosure is reduced significantly relative to an enclosure without a solar shield. The invention takes advantage of the fact that the surfaces of the sealed electronics enclosure are not exposed to solar radiation and yet, with adequate ventilation of the solar shield, can be exposed to cooling air near the outdoor ambient temperature. The ventilation openings in the solar shield, though they may admit rain and dust along with cooling air, are sized to exclude bees and wasps which are particularly troublesome in outdoor enclosures.
According to one aspect, the present invention comprises an apparatus for enclosing electronics. The apparatus includes an outer enclosure having a plurality of perforations substantially uniformly distributed about its surface, and an inner enclosure positioned within the outer enclosure. Preferably, the inner enclosure has one or more electronic components selectively positioned inside. It is desirable for the outer enclosure to be configured and dimensioned to be spaced from the inner enclosure.
According to this embodiment, each of the plurality of perforations substantially prevent sunlight from directly striking an outer surface of the inner enclosure. At the same time, each of the plurality of perforations allow air to pass to the space between the inner and outer enclosure. The perforations are configured and dimensioned such that about 95% or more of the sunlight that strikes each of the plurality of perforations from an angle of about 45 degrees or more relative to normal are substantially prevented from striking the surface of the inner enclosure.
In one embodiment the outer enclosure preferably comprises plastic that has a thickness of between about 2.5 mm and about 3.5 mm. The width of the perforations may be between about 5.5 mm and about 6.5 mm. Finally, the height of the perforations is preferably between about 2.5 mm and about 3.5 mm.
According to another embodiment, the present invention comprises an apparatus for enclosing electronic components. The apparatus includes a first housing having one or more electronic components selectively positioned therein, and a second housing configured and dimensioned to enclose the first housing. It is desirable for the second housing to include a plurality of perforations that substantially prevent sunlight from directly striking the first housing. The second housing is preferably spaced from the first housing by a distance of between about 10 mm and about 14 mm. Preferably, the height of the perforations is between about 2 mm and about 4 mm, and the width of the perforations is between about 4 mm and about 8 mm.
According to yet another embodiment, the present invention comprises an apparatus for enclosing electronic devices. The apparatus includes an inner enclosure having one or more electronic devices positioned inside, and an outer enclosure configured and dimensioned to surround the inner enclosure. The inner enclosure is preferably separated from the outer enclosure by a gap that is between about 8 mm and about 16 mm. The outer enclosure comprises a plurality of perforations, each of which allow air to enter the gap.
According to this embodiment, the outer enclosure comprises plastic, and the plurality of perforations are uniformly distributed on the surface of the outer enclosure. The plurality of perforations substantially prevent sunlight from directly striking a surface of the inner enclosure. For instance, between about 80% and about 100% of the sunlight that strikes the outer enclosure from an angle of about 45° or more relative to normal is prevented from directly striking the surface of the inner enclosure.

BRIEF DESCRIPTION OF THE DRAWINGS

Further features and advantages of the invention can be ascertained from the following detailed description that is provided in connection with the drawings described below:
FIG. 1 shows an exemplary embodiment of the present invention;
FIG. 2 shows a side view of one embodiment of the present invention; and
FIG. 3 shows a cross-section of a ventilation hole according to one aspect of the present invention.

DETAILED DESCRIPTION OF THE PREFERRED EMBODIMENTS

Manufacturers of electrical enclosures prefer to produce the enclosures in high volume in order to reduce their cost. This requirement tends to favor a molded plastic enclosure cooled by natural convection, although such a design does not dissipate the internally generated heat of the electronics effectively enough for a compact design with long life. The housing of electronic equipment on the exterior of a residence for applications such as fiber to the premises introduces a cooling problem due to the following requirements: (i) compact packaging; (ii) sealing against contamination; (iii) additional thermal loading from solar radiation; (iv) low cost due to widespread deployment; and (v) low maximum device temperatures for maximum life and reliability. Temperature rise due to solar heating is particularly problematic in sealed enclosures. In enclosures that hold electronics that have a low operating power, temperature rise due to solar loading can far exceed temperature rise due to self-heating of the electronics.
To overcome this and other disadvantages, the present invention provides an electronics enclosure that comprises a solar shield. Generally, the enclosure comprises an inner enclosure that isolates the electronics from the outside environment. The inner enclosure, in turn, is surrounded by an outer enclosure that includes perforations over at least a portion of its surface area. The perforations are configured and dimensioned such that air is capable of passing into a space between the inner and outer enclosures. The flow of air around the inner enclosure allows heat to be dissipated, cooling the electronics positioned within it. At the same time, the perforations are configured and dimensioned such that the inner enclosure is shielded from solar radiation. Preferably, the perforations prevent the entry of insects, such as bees and wasps, into the space between the inner enclosure and the outer enclosure.
The enclosure may house any type of equipment. Preferably, electronic equipment is housed within the enclosure. However, it is contemplated that other non-electronic hardware may also be enclosed. The non-electronic equipment may comprise materials that support or otherwise interact with the electronic equipment. The present invention may be used in combination with other elements, e.g., heat sinks. An example of a heat sink that may be used is disclosed in a co-pending U.S. Application filed on Dec. 13, 2006, entitled “Heat Sinks for Electronic Enclosures,” Attorney Docket No. 19546.0005, the entirety of which is incorporated herein by reference.
In one embodiment, the inner and outer enclosures comprise the same material. In other embodiments, however, the inner and outer enclosures may comprise different materials. It is desirable for the enclosures to comprise a material that reduces cost and is lightweight. As such, the enclosures are preferably comprised of a plastic. However, the enclosures, or portions thereof, may comprise a variety of materials other than plastic. These materials may include, for example, metal, alloys, wood, glass, composites, fiberglass, and the like.
Each enclosure may have any desired dimensions, as will be appreciated by those skilled in the art. In other words, the height, width, and depth of each enclosure may be chosen according to a particular application. Factors that may be considered include, but are not limited to, the type of electronic equipment enclosed, the dimensions of the electronic equipment and/or hardware enclosed, the space available outside a residence, and the like.
FIG. 1 is a diagram showing one exemplary embodiment of the present invention. FIG. 1 shows the enclosure of the present invention in an unassembled position in order to facilitate the explanation of this embodiment of the present invention. It is desirable for the outer enclosure to include two parts, e.g., a solar shield 10 and a mounting bracket 12. Similarly, the inner enclosure includes a first portion 14 and a second portion 16.
The solar shield 10 and the mounting bracket 12 may comprise any desired dimensions. Preferably, however, the dimensions of the two parts 10, 12 are selected such that they are able to enclose the inner enclosure. An example of this is shown in FIG. 2, which is a side view of the FIG. 1 embodiment in the assembled position. Similarly, the dimensions of the first portion 14 and the second portion 16 of the inner enclosure may be selected such that the electronics and/or other non-electronic hardware may be fully enclosed.
In one embodiment, the outer enclosure of the present invention is mounted to the wall, or another portion, of a residence. As such, the mounting bracket 12 preferably includes one or more mounting feet that enable the mounting bracket 12 to rest flush against the surface of the wall of the residence. Optionally, the mounting bracket 12 may include a fastener, e.g., a screw, bolt, and the like, that passes from the inside of the mounting bracket 12, through the back wall of the bracket 12 (facing the wall), in order to fasten the mounting bracket 12 to the surface of the wall. Skilled artisans will recognize that other fastening mechanisms may be employed as desired. For instance, the fasteners may pass through the mounting feet 18, or alternately the surface of the mounting feet 18 that contacts the wall may include an adhesive. In other embodiments, combinations of these and other fastening mechanisms known to those skilled in the art may be used.
The solar shield 10 and the mounting bracket 12 may be connected in any desirable manner, using an fastening mechanism known to those skilled in the art. Preferably, the solar shield 10 and the mounting bracket 12 are connected through selectively engageable parts. For example, in one embodiment the solar shield 10 may include a protrusion, and the mounting bracket 12 may include a corresponding recess. In order to connect the solar shield 10 and the mounting bracket 12, the protrusion may be inserted into the recess. At least a portion of the protrusion may be configured and dimensioned such that it is slightly larger than the opening of the recess, such that friction forces provide resistance against disengagement. Alternately, the solar shield 10 and the mounting bracket 12 may comprise a “lock and key” mechanism that prevents their disengagement. In still other embodiments, adhesives, Velcro, hinges, or the like may be employed. Apparatus and methods for connecting two portions of an enclosure are well known to skilled artisans, any of which may be used, and the present invention is not intended to be limited to any particular apparatus or method of engagement.
In a manner similar to the outer enclosure, the inner enclosure may also employ any of the apparatus and methods of engagement described above. In one embodiment, however, it is desirable for the inner enclosure to be tightly sealed when it is engaged. This provides the advantage of isolating the electrical components within the inner enclosure from any environmental factors that may affects its operation, e.g., dust, wind, moisture, and the like. An example of a sealed engagement 30 is illustrated in FIG. 2. The inner enclosure, according to one embodiment, may be configured and adapted to receive wires 32, cables, and the like that may be connected to the electronic components, as shown in FIG. 2.
The sealed engagement 30 of the inner enclosure may be formed in a similar manner as the engagement described above. Skilled artisans will recognize that additional materials may be necessary to form a seal, such as rubber, metal, and the like. Both the inner and outer enclosure, despite the engagement of its parts, should be capable of being separated to allow access to both the area between the inner and outer enclosure as well as the electrical components positioned within the inner enclosure. To facilitate the engagement of the outer enclosure and the inner enclosure, the inner enclosure preferably includes hinges 20 that are capable of engagement with the parts of the outer enclosure.
As shown in FIG. 1, solar shield 10 and the mounting bracket 12 of the outer enclosure include a plurality of ventilation holes 22, or perforations. The present invention is not intended to be limited to any number of ventilation holes 22. The ventilation holes 22 may be selectively positioned in any desirable manner. According to one aspect, the ventilation holes 22 may be positioned such that the air flow results in a maximum amount of cooling of the electronic components located within the inner enclosure. The ventilation holes 22 are preferably located on both parts of the outer enclosure, i.e., the solar shield 10 and the mounting bracket 12. In other embodiments, however, the ventilation holes 22 may only be located on one part of the outer enclosure. It is desirable for the ventilation holes 22 to be uniformly located over the surface of the outer enclosure. One advantage of uniformly positioning the ventilation holes 22 is that cooling may be improved by maximizing air intake.
FIG. 3 is a diagram showing a cross-sectional view of an exemplary ventilation hole 22 of FIG. 1. The ventilation holes 22 are preferably configured and dimensioned such that they are able to admit air while preventing the entry of larger debris and even insects, e.g., bees and wasps, that are often troublesome in outdoor enclosures. The ventilation holes 22 may comprise any desired shape known to those skilled in the art including, but not limited to, circular, oval, any polygon, or even an irregular shape. Preferably, however, the ventilation holes 22 are rectangular. Furthermore, each of the plurality of ventilation holes 22 may have the substantially same dimensions and shape, or alternately the ventilation holes 22 may have substantially different dimensions and shape.
In one embodiment, the height 24 of the ventilation hole 22 may be varied. Preferably, the height 24 of the ventilation hole 22 is between about 1.5 mm and about 4.5 mm. More preferably, the height 24 of the ventilation hole 22 is between about 2.5 mm and about 3.5 mm. Most preferably, the height 24 of the ventilation hole 22 is between about 2.85 and about 3.15 mm.
In another embodiment, the height 24 of the ventilation hole 22 is preferably about 5 mm or less. More preferably, the height 24 of the ventilation hole 22 is about 4 mm or less. Most preferably, the height 24 of the ventilation hole 22 is about 3 mm or less. In yet another embodiment, the height 24 of the ventilation hole 22 is preferably about 2 mm or greater. More preferably, the height 24 of the ventilation hole 22 is about 3 mm or greater. Most preferably, the height 24 of the ventilation hole 22 is about 4 mm or greater.
The width 26 of the ventilation hole 22 may also be varied as desired. In one embodiment, the width 26 of the ventilation hole 22 is preferably between about 3 mm and about 9 mm. More preferably, the width 26 of the ventilation hole 22 is between about 4 mm and about 8 mm. Most preferably, the width 26 of the ventilation hole 22 is between about 5 mm and about 7 mm.
According to another aspect of the present invention, the width 26 of the ventilation hole 22 is about 12 mm or less. More preferably, the width 26 of the ventilation hole 22 is about 8 mm or less. Most preferably, the width 26 of the ventilation hole 22 is about 6 mm or less. According to still another embodiment, the width 26 of the ventilation hole 22 is preferably about 3 mm or greater. More preferably, the width 26 of the ventilation hole 22 is about 6 mm or greater. Most preferably, the width 26 of the ventilation hole 22 is about 8 mm or greater.
As shown in FIG. 3, the depth 28 of the ventilation hole 22, and thus the thickness of the outer enclosure, may also be varied as desired. In one embodiment, the depth 28 of the ventilation hole 22 is preferably between about 1.5 mm and 4.5 mm. More preferably, the depth 28 of the ventilation hole 22 is between about 2 mm and about 4 mm. Most preferably, the depth 28 of the ventilation hole 22 is between about 2.5 mm and about 3.5 mm.
In another aspect of the present invention, the depth 28 of the ventilation hole 22 is preferably less then about 10 mm. More preferably, the depth 28 of the ventilation hole 22 is less than about 6 mm. Most preferably, the depth 28 of the ventilation hole 22 is less than about 3 mm. According to another embodiment, the depth 28 of the ventilation hole 22 is preferably greater than 2 mm. More preferably, the depth 28 of the ventilation hole 22 is greater than about 3 mm. Most preferably, the depth 28 of the ventilation hole 22 is greater than about 6 mm.
To facilitate movement of air, the outer enclosure is spaced a sufficient distance away from the inner enclosure, as illustrated in the FIG. 3 embodiment. At the same time, it is desirable to minimize the distance of between the inner and outer enclosure in order to reduce the amount of space that the enclosure occupies. In one embodiment, the distance between the outer enclosure and the inner enclosure is preferably between about 6 mm and about 18 mm. More preferably, the distance between the outer enclosure and the inner enclosure is between about 9 mm and about 15 mm. Most preferably, the distance between the outer enclosure and the inner enclosure is between about 11 mm and about 13 mm.
In another embodiment, the distance between the outer and inner enclosures is preferably about 25 mm or less. More preferably, the distance between the outer and inner enclosures is about 20 mm or less. Most preferably, the distance between the outer and inner enclosures is about 15 mm or less. According to other embodiments, the distance between the outer and inner enclosures is preferably about 8 mm or greater. More preferably, the distance between the outer and inner enclosures is about 15 mm or greater. Most preferably, the distance between the outer and inner enclosures is about 25 mm or greater.
One advantage of configuring and dimensioning the ventilation holes 22 in the manner described above is that sunlight can be prevented from directly striking the surface of the inner enclosure, reducing the amount of heat to which the electronic components are exposed. In other words, the ventilation holes 22 are preferably configured and dimensioned such that they substantially minimize the amount of sunlight that strikes the inner enclosure.
Those skilled in the art will recognize that sunlight strikes the horizontal and vertical surfaces of the shield at angles of about 45° or more, relative to normal, during much of the day. As illustrated in FIG. 3, sunlight that strikes the ventilation holes 22 of the solar shield 10 from these angles (about 45° or more relative to normal) is substantially prevented from passing through to the inner enclosure. Preferably, about 80% or more of the sunlight that strikes the outer enclosure is prevented from directly striking the surface of the inner enclosure. More preferably, about 90% or more of the sunlight that strikes the outer enclosure is prevented from directly striking the surface of the inner enclosure. Most preferably, about 95% or more of the sunlight that strikes the outer enclosure is prevented from directly striking the surface of the inner enclosure.
According to another embodiment, between about 80% and about 100% of the sunlight that strikes the outer enclosure is prevented from directly striking the surface of the inner enclosure. More preferably, between about 90% and about 100% of the sunlight that strikes the outer enclosure is prevented from directly striking the surface of the inner enclosure. Most preferably, between about 99% and about 100% of the sunlight that strikes the outer enclosure is prevented from directly striking the surface of the inner enclosure.
As shown in FIG. 2 and described above, one embodiment of the present invention may be mounted or otherwise attached and/or secured to the exterior of a residence, preferably a wall of the residence. In its sealed configuration, the present invention allows air to pass through the ventilation holes 22 of the outer enclosure. The selectively positioned ventilation holes 22 allow air to pass through the outer enclosure. At the same time, the ventilation holes 22 are configured and dimensioned such that most of the sunlight that strikes the outer enclosure does not directly strike the inner enclosure. Moreover, the ventilation holes 22 substantially prevent the entry of insects and other objects of similar dimensions. As the air enters the space between the inner and outer enclosure, heat is effectively removed by natural convection. One advantage of the present invention, therefore, is that the surface temperature of the inner enclosure is reduced significantly.
Although the present invention has been described with reference to particular embodiments, it will be understood to those skilled in the art that the invention is capable of a variety of alternative embodiments within the spirit of the appended claims.

Claims

1. An apparatus for enclosing electronics, comprising:

an outer enclosure having a plurality of perforations substantially uniformly distributed about its surface; and

an inner enclosure positioned within the outer enclosure, wherein the inner enclosure has one or more electronic components selectively positioned inside;

wherein the outer enclosure is configured and dimensioned to be spaced from the inner enclosure.

2. The apparatus of claim 1, wherein each of the plurality of perforations substantially prevent sunlight from directly striking an outer surface of the inner enclosure.

3. The apparatus of claim 1, wherein each of the plurality of perforations allow air to pass to the space between the inner and outer enclosure.

4. The apparatus of claim 1, wherein about 95% or more of the sunlight that strikes each of the plurality of perforations from an angle of about 45 degrees or more, relative to normal, are substantially prevented from striking a surface of the inner enclosure.

5. The apparatus of claim 1, wherein the outer enclosure comprises plastic.

6. The apparatus of claim 1, wherein the width of the perforations is between about 5.5 mm and about 6.5 mm.

7. The apparatus of claim 1, wherein the height of the perforations between about 2.5 mm and about 3.5 mm.

8. An apparatus for enclosing electronic components, comprising:

a first housing having one or more electronic components selectively positioned therein; and

a second housing configured and dimensioned to enclose the first housing;

wherein the second housing includes a plurality of perforations that substantially prevent sunlight from directly striking the first housing.

9. The apparatus of claim 8, wherein the plurality of perforations are uniformly distributed about the surface of the second housing.

10. The apparatus of claim 8, wherein the second housing comprises plastic.

11. The apparatus of claim 8, wherein the thickness of the second housing is between about 2.5 mm and about 3.5 mm.

12. The apparatus of claim 8, wherein the second housing is spaced from the first housing.

13. The apparatus of claim 12, wherein the space between the second housing and the first housing is between about 10 mm and about 14 mm.

14. The apparatus of claim 8, wherein:

the height of the perforations is between about 2 mm and about 4 mm; and

the width of the perforations is between about 4 mm and about 8 mm.

15. An apparatus for enclosing electronic devices, comprising:

an inner enclosure having one or more electronic devices positioned inside; and

an outer enclosure configured and dimensioned to surround the inner enclosure;

wherein the inner enclosure is separated from the outer enclosure by a gap;

and wherein the outer enclosure comprises a plurality of perforations, wherein each of the plurality of perforations allow air to enter the gap.

16. The apparatus of claim 15, wherein the outer enclosure comprises plastic.

17. The apparatus of claim 15, wherein the plurality of perforations are uniformly distributed on the surface of the outer enclosure.

18. The apparatus of claim 15, wherein the plurality of perforations substantially prevent sunlight from directly striking a surface of the inner enclosure.

19. The apparatus of claim 15, wherein between about 80% and about 100% of the sunlight that strikes the outer enclosure from an angle of about 45° or more relative to normal is prevented from directly striking a surface of the inner enclosure.

20. The apparatus of claim 15, wherein the gap is between about 8 mm and about 16 mm.