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CROSS-REFERENCE TO RELATED APPLICATIONS 
     This application is a continuation of U.S. patent application Ser. No. 12/942,016, filed Nov. 8, 2010, which claims priority to U.S. Provisional Application No. 61/259,436, filed Nov. 9, 2009 and U.S. Provisional Application No. 61/267,766, filed Dec. 8, 2009, which are incorporated herein by specific reference. 
    
    
     BACKGROUND OF THE INVENTION 
     1. The Field of the Invention 
     The invention relates to air containment systems for computer server racks. In particular the invention relates to a containment roof for computer server racks. 
     2. The Relevant Technology 
     Many companies have data centers either for the company&#39;s use or for selling data services to others. Frequently many computers are pooled into clusters and placed in many racks. These racks may be placed in rows within the data center. The electronic equipment in the data centers includes servers, computers, routers and the like. They may also include backup servers, which can take over the function of primary servers in the event of a primary server failure. They are typically co-located with the network switches and/or routers which enable communication between the different parts of the cluster and the users of the cluster. The computers, routers, power supplies, and related electronics are typically mounted on 19-inch racks in a server room or data center. 
     All computer equipment produces heat when it is in operation. For this purpose, a fan is typically installed in the computer. The fan draws cooler air from the environment over the heated internal parts. Heated air is exhausted back into the environment. In large data centers, the heat from many computers results in significant heating of the data center environment. Many large air conditioning units are used to cool the data center environment. 
     To reduce the cost of cooling data centers, the computer racks can be arranged in rows with the equipment in adjoining rows. The computers in the racks are situated so that hot and cool aisles are created. In the hot aisle the fans on the equipment in adjoining rows exhausts the heated air form the equipment. In the cool aisle, conditioned air is draw into and cools the equipment. 
     Containment devices such as doors, roofs, as well as vertical curtains are used to contain the conditioned air within the cool row. In this way the heated air and conditioned air do not mix, thereby maximizing the cooling effect on the equipment while keeping the costs of cooling down. 
     Most fire codes and best practices require that at least the roofs of the containment systems be configured to allow fire suppression systems to spray within the contained aisle in the event of fire. 
     Most of the roofs of available containment systems use a series of panels that separate when a fire is detected. These panels may drop to the floor potentially striking persons in the data center or a firefighter with debris. Further the fallen panels create a tripping hazard as persons attempt to leave the building and as firefighters attempt to clear the building and/or suppress the fire. 
     BRIEF SUMMARY OF THE INVENTION 
     An air containment system for separating conditioned air from the heated exhaust of a computer rack aisle is presented. The containment system may include a roof system with retractable canopy. The retractable canopy has a retracted position and an extended position. A retractor may transition the canopy from the extended position to a retracted position. In the extended position, the canopy may cover at least a portion of the top of the computer rack aisle, and in the retracted position the canopy may be substantially removed from above the computer rack aisle. 
     A selectively releasable retainer may retain the canopy in the extended position. When the environment in which the computer rack aisle is located is exposed to a predetermined condition, the retainer may release the canopy to return to the retracted position. Such predetermined conditions may include a fire, excessive heat, failure of the air conditioning system, or other condition that may result in damage to electronic equipment that may be stored within the computer racks. The predetermined condition may be an environmental temperature in the range from about 90° F. to about 225° F. In certain embodiments, the predetermined condition may be an environmental temperature in the range from about 115° F. to about 145° F. In yet other embodiments, the predetermined condition may be an environmental temperature of about 135° F. 
     The rack roof may have a have a heat sensitive retainer such as a fusible link, such as a mechanical fusible link, a mechanical fusible chain, a mechanical fusible wire, and an electrically actuated fusible link. The selectively releasable retainer may also be an electronically actuated retainer that selectively retains or releases the canopy based on a signal received from a sensor, a fire suppression system, human input, or the like. 
     The canopy may be a flexible tarp made of a material such as vinyl, plastic, cotton, wool, poly vinyl chloride other natural and synthetic materials, or a combination thereof. The canopy may be fire resistant. 
     The canopy may have first and second lateral sides. One or more flanges may be attached to or made an integral part of the canopy. Generally such flanges run along or near the first and/or second lateral sides from a position near a front end of the canopy to a position near or near the rear end of the canopy. By way of example and not limitation, the flanges may be constructed of a flexible plastic, rubber, aluminum or like materials attached to or near the side of the canopy. Alternatively, the flange may be an integral part of the canopy molded in the canopy material or rolled or enclosed within the first and or second lateral edges of the canopy. A canopy guide track may be provided to be attached along the top portion of the computer racks. The canopy guide track may have a channel configured to receive therein the one or more flanges. Likewise the flanges may be configured to be received within channel of the track. 
     A variety of canopy retractors may be employed within the present invention. For example, in certain embodiments, the canopy may be connected to a spool configured to receive the canopy thereon. Such spools can be operably connected to a retracting spring or a motor. The retracting spring or motor can be configured to retrieve the canopy from the extended position to the retracted position when the selective retainer is exposed to the predetermined environmental condition. When a retracting spring is used, the spring may bias the canopy toward the retracted position. When a motor is used the motor may be activated to retrieve the canopy from the extended position to the retracted when the selective retainer is exposed to the predetermined environment condition. In such embodiments, a selective retainer may be the unactivated motor. 
     The canopy has a length that will vary depending on the length of the racks on which it is deployed. In some embodiments, the canopy has a length in the range from about 8 feet to about 50 feet. In certain other embodiments the canopy has a length in the range from about 14 feet to about 30 feet. 
     Additionally the width of the canopy should adequately cover the rack aisle. The canopy may have a width in the range from about 3 feet to about 8 feet. In other configurations, the canopy may have a width in the range from about 4 feet to about 7 feet. 
     The present invention also relates to an air containment system for a computer rack aisle. Such containment systems may have one, two, or more canopy systems. The canopy system may include a canopy, having an extended position and a retracted position. A canopy retractor can move the canopy from the extended position to the retracted position. A selectively releasable retainer can retain the canopy in the extended position release the canopy from the extended position when a predetermined condition is met. 
     When two or more canopies are used, they be releasable joined along at least one side of the canopies when the canopies are in the extended position. The air containment system may have canopies that are deployable in a substantially horizontal orientation or a substantially vertical orientation. 
    
    
     
       BRIEF DESCRIPTION OF THE DRAWINGS 
       Various embodiments of the present invention will now be discussed with reference to the appended drawings. It is appreciated that these drawings depict only typical embodiments of the invention and are therefore not to be considered limiting of its scope. 
         FIG. 1  is a perspective view of a computer rack aisle having a retractable roof system according to the present invention. 
         FIG. 2A  is a perspective view of a first portion of a computer rack aisle roof system in accordance with the present invention. 
         FIG. 2B  is a perspective view of a second portion of a computer rack aisle roof system in accordance with the present invention. 
         FIG. 3  is an exploded view of a retractable canopy in accordance with the present invention. 
         FIG. 4  is a perspective view of an additional embodiment of an air containment system in accordance with the present invention. 
         FIG. 5  is an additional embodiment of a retractable roof rack canopy in accordance with the present invention. 
     
    
    
     DETAILED DESCRIPTION OF THE PREFERRED EMBODIMENTS 
     Before the present system and methods of use thereof for producing an accurate likeness are disclosed and described, it is to be understood that this invention is not limited to the particular configurations, process steps, and materials disclosed herein as such configurations, process steps, and materials may vary somewhat. It is also to be understood that the terminology employed herein is used for the purpose of describing particular embodiments only and is not intended to be limiting since the scope of the present invention will be determined by the appended claims and equivalents thereof. 
     As used herein, “comprising,” “including,” “containing,” “having,” “characterized by,” and grammatical equivalents thereof are inclusive or open-ended terms that do not exclude additional, unrecited elements or method acts. 
     As used herein, “about” means reasonably close to, a little more or less than the stated number or amount, or approximately. 
     As used herein, “exemplary” means serving as an example of. The use of the term “exemplary” herein in connection with a particular embodiment is not to be construed as the particular embodiment being preferred over any other embodiment. 
     Referring to  FIGS. 1-5  exemplary embodiments of a computer aisle air containment system  10  having a computer aisle roof system  12  in accordance with the present invention is shown. 
     The air containment system  10  can be used in computer data centers where electronic equipment (not shown) such as computers, servers, routers, etc., is located in many server racks  18 . The electronic equipment produces a large amount of heat that must be expelled from the equipment to prevent damage to the equipment and potentially a fire. To cool the equipment, small electric fans are generally placed inside the equipment. The fans draw cooler air from the environment through the equipment. This air cools the equipment and is discharged as heated air back into the environment. 
     When large amounts of electronic equipment are located in a data center, the collective heat produced by the pooled equipment can rapidly heat the room in which it is located. To keep the room and the equipment cool, a cooling system is provided to the room. 
     However, cooling the entire room is inefficient. Therefore, containment systems have been used that isolate the heated exhaust air from the conditioned cooler air. Such containment systems may create a cool aisle  20  where conditioned air is supplied through the floor or otherwise supplied and a hot aisle  22  where the heated exhaust air is discharged from the electronic equipment and may be vented from the building. The racks  18  and the computer equipment therein create walls for the cooled aisle  20 . End caps such as door unit  14  and/or curtain  24  contain the conditioned air within the cooled aisle  20 . A roof system  12  can be employed to contain the conditioned air within the cooled aisle. It will be appreciated, that while the current practice is to contain cooled air within the cooled aisle  20 , the racks  18  and equipment could be rearranged so that the hot air is contained within the aisle and the cooled air is the environmental air external to the aisle. 
     The present invention includes a roof system  12  with a retractable canopy  26 . The canopy  26  can flexible so that is able to be wound around a spool  28  ( FIG. 3 ) or otherwise retracted by a retractor. The canopy  26  may be constructed of natural or man-made materials. Such materials may include, but are not limited to cotton, wool, plastic, vinyl, nylon, polyester, polyvinyl chloride, polycarbonate, etc. The material selected for the canopy  26  can be fire retardant. Additionally a transparent or translucent canopy  26  can allow the light from the data center room to filter into the cool aisle  20 . 
     The retractable canopy  26  has an extended position wherein at least a portion of the canopy  26  covers the space above the cool aisle  20  and a retracted position wherein the canopy  26  is substantially removed from above the cool aisle  20 . The canopy  26  can have reinforcements  44  ( FIG. 2A ) applied to its front end  56  distal from the retractor. Such reinforcements can be one or more folds in the canopy  26  or may include metal, wood, paper, plastic, other materials, etc. that serve to strengthen the front end  56 . 
     The canopy has a length  36  that will vary depending on the length of the racks aisle  19  on which it is deployed. In some embodiments, the canopy has a length  36  in the range from about 8 feet to about 50 feet. In certain other embodiments, the canopy has a length  36  in the range from about 14 feet to about 30 feet. In a present embodiment, the canopy has length of about 20 feet. For longer aisles, two or more canopies  26  and retractors  27  can be used. 
     Additionally the width  34  of the canopy should adequately cover the rack aisle  19 . The canopy may have a width  34  in the range from about 3 feet to about 8 feet. In other configurations, the canopy  26  may have a width  34  in the range from about 4 feet to about 7 feet. In a present embodiment, the canopy has a width  34  of about 6½ feet. 
     If a rack aisle has missing racks  18  or racks that are shorter than other racks, curtains  24  can be hung from the rail  46  to cover the opening. These curtains may be made from the same or similar materials as the canopy  26 . 
     The spool  28  can be a spring loaded spool that biases the canopy toward the retracted positioned as shown in  FIG. 2A . Referring to  FIG. 3  with continued reference to  FIGS. 1 and 2 , a simplified spring loaded spool  28  that may be used with the present invention is presented. The spool  28  has an inner spool  60  that is operably linked to a spring  62 . The spring  62  is also operably linked to an outer spool  64 . The canopy  26  is attached to and wound around outer spool  64 . The canopy may be attached to the outer spool  64  with fasteners such as screws or rivets or may be inserted into a groove within the outer spool  64  configured to receive and capture the canopy  26 . As the canopy  26  is pulled from the retracted position ( FIG. 2A ) into the extended position ( FIG. 1 ), the spring  62  is placed under tension. This tension creates a force F that continually biases the canopy  26  to the retracted position. When the selectively releasable retainers  38  ( FIG. 2A ) release the canopy, the spring  62  turns the outer spool  64  and retracts the canopy  26 . 
     Selectively releasable retainers  38  can be used to selectively hold the canopy  26  in the extended position  30 . The retainers  38  can be configured to release the canopy  26  to retract to the retracted position when a predetermined condition is met. The selectively releasable retainers may be a fusible link  40  such as mechanical fusible link, a mechanical fusible chain, a mechanical fusible wire, and an electrically actuated fusible link. 
     The predetermined condition under which the selective retainers  38  release the canopy may vary depending on the reason for the release. For example, the retainer  38  may be selected to release the canopy when the predetermined condition is the detection of a fire. The fire suppression system can send a signal to an electrically actuated fusible link or other electronic retainer  38  to release the retainer to the retracted position. The preselected condition can also be the failure of a cooling system. Additionally, the temperature of the environment may indicate the presence of a fire or the catastrophic failure of the cooling system. The predetermined condition can be an environmental temperature in the range from about 90° F. to about 225° F. In other embodiments, the predetermined condition can be an environmental temperature in the range from about 115° to about 145° F. In yet other embodiments the predetermined condition is an environmental temperature of about 135° F. 
     With reference to  FIGS. 2A and 2B , the roof system  12  can include a rack assembly  41  for attaching the roof system  12  to the rack aisle  19 . The rack assembly  41  can include housing  42  that covers the spool  28  ( FIG. 3 ) and the retracted canopy  26 . The housing  42  may be mounted to an end of the computer rack aisle  19 . The assembly  41  can also include side rails  46  to provide lateral support to the assembly  41 . Aisle cross supports  50  may be provided distally from the housing  42  near the front portion  56  ( FIG. 1 ) of the rack assembly  41  or at any desired intervals internal to the rack assembly  41 . End support  48  can provide additional stability to the rack assembly and provide for an attachment point for the selectively releasable retainers  38 . 
     The rails  46  can include channels  47 . The channels  47  can be configured to receive edges  51  of the canopy  26  to guide the canopy from the extended position to the retracted position or vice versa. Additionally, the canopy  26  may include flanges  52  that run from a position approximate a front portion  56  of the canopy  26  and to a position approximate a rear portion  58  of the canopy. The flanges  52  can hold the canopy edges  51  within the channels  47 . The side rails  46  can be relatively air tight on top of the racks  18 . The rails  46  may incorporate adjustable standoffs for some applications. 
     The housing  42  can be used to cover the retractor  27  and spool assembly  28 . Housing  42  made from aluminum or other fire retardant materials can protect the retractor and spool assembly while giving added fire resistance to a retracted canopy  26 . 
     Referring now to  FIG. 4 , an alternative embodiment of a roof system  112  is shown. In this embodiment, the canopy  126  is deployed in a substantially vertical position. Retractor  127  is mounted to the ceiling of the room in which the racks  118  are located. Alternatively the retractor  127  can be mounted to the top of the racks  118 . The when the canopy  126  is extended, it is connected to the top of the rack  118  or ceiling by selectively releasable retainers  138 ,  142  as previously discussed. When the retainers  138 ,  142  release the canopy  126 , canopy  26  is retraced by force F into the housing  142 . One or more additional canopies  126  may be operably connected to additional retractors  127 . These multiple canopies along with the ceiling of the room, may serve as the roof unit of the air containment system. To further secure the air within the containment system, releasable fasteners  172  can be used to secure the edges of adjoining canopies  126 . Such fasteners  172  can be hook and latch fabric fasteners, magnets, fusible links, or the like. 
     Referring now to  FIG. 5 , an alternative embodiment of a roof system  212  is shown. The roof system uses a canopy  226  and selectively releasable retainers  238  as discussed with  FIG. 1 . In this embodiment electric motor  280  is connected to spool  228  and power supply  282 . When motor  280  is used retainers  238  may also be the motor or an impulse to the motor. Power supply  282  can be a battery or the motor may be plugged into an outlet. 
     Spool  228  is operably linked to cord  284 . The distal end of the cord  284  is connected to the distal end of the canopy  226  and woven through the canopy through reinforced holes  186 . When the motor is activated in the event of a predetermined condition, the chord is wound around spool  228 . The retracting cord  286  pulls the canopy  226  into a retracted position. 
     The present invention may be embodied in other specific forms without departing from its spirit or essential characteristics. The described embodiments are to be considered in all respects only as illustrative and not restrictive. The scope of the invention is, therefore, indicated by the appended claims rather than by the foregoing description. All changes which come within the meaning and range of equivalency of the claims are to be embraced within their scope.

Summary:
A roof for a computer rack aisle is provided. The roof has a canopy that may be flexible and/or fire-resistant. The canopy has a retracted position and an extended position. In the extended position the canopy may cover the top of an aisle between two computer racks, while in the retracted position the aisle can be uncovered. A canopy retractor is provided to move the canopy from the extended position to the retracted position when a predetermined condition is met. The canopy has first and second lateral edges that are slidably received within the channels of guide tracks to facilitate the smooth movement from the extend position to the retracted position.