Abstract:
An improved micro-cabinet or vault that facilitates the underground storage of electronic equipment, such as instrumentation for wireless telecommunications antenna systems. The micro-cabinet of the present invention is formed of a metal weldment, preferably stainless steel, which enables it to be made comparatively small without sacrificing strength or equipment security. Because of its reduced size, the micro-cabinet can easily be placed in a public right of way. The micro-cabinet is substantially water-tight with a cooling system and a water evacuation system.

Description:
FIELD OF THE INVENTION 
     The present invention relates generally to enclosures for electronic equipment and, more particularly, to a micro-cabinet or vault that facilitates the underground storage of electronic equipment, such as instrumentation for wireless telecommunications transceiver systems. 
     BACKGROUND OF THE INVENTION 
     Public demand for wireless telecommunications has grown at a tremendous rate. An increasing number of people rely on their wireless phones for an increasing number of uses including voice, messaging, data, video, and internet access. This enormous public demand has in turn fueled the need for additional carrier antenna sites to provide expanded wireless coverage to communities. 
     As the need for additional antenna sites has grown, so too has the installation restrictions set by many municipalities. Cell phone carriers are being required to place their transceiver equipment in an aesthetically pleasing manner. In many municipalities the planning departments are unwilling to grant permit applications for unsightly tower installations. There is also a growing tendency for many of these municipalities to require even the smallest of transceiver circuitry units to be placed underground, and for the antennas to be disguised or stealthed. 
     A partial, but elegant, solution for many carriers has been to disguise their antennas by placing them atop of street light standards or other vertical structures, such as signs, etc., along existing right of ways. However, no such solution is currently available to cell phone carriers for burying their transceiver circuitry. 
     The units housing the transceiver or transmitting and receiving circuitry for wireless telecommunications systems come in different sizes, and have different power and transceiver configurations. The standard or “macro-cell” unit is a compact base transceiver station (“BTS”), which stores six (6) to eight (8) transceivers or radios requiring 1800 to 2200 watts of power. The smallest unit currently used, primarily where a mono-pole transceiver system is inappropriate, is a “micro-cell”, which typically houses one (1) to two (2) transceivers requiring 170 to 600 watts of power. Currently, the vaults available to place the compact BTS&#39;s or micro-cells underground tend to be too large to be useful in right of way applications many carriers are looking to implement. Typically these vaults are made of concrete, which for strength and equipment security reasons require thick walls and considerable overall size. Because of their overall size, there are limits as to where these vaults can be placed. 
     In addition, the problem with any self-contained, sealed underground vault is that the telecommunications equipment enclosed therein generates heat, which ultimately damages or destroys the equipment. Moisture, either from evaporation or flooding from rain, can also damage or destroy the equipment. These problems are typically solved by using an air conditioner and dehumidifier in conjunction with a water pump, which add to the complexity and cost of the vault. Most existing vaults include an unattractive heat exchanger that is located above ground, or an underground heat exchanger that is quite costly to construct and install, and adds to the overall space needed to bury the vault. 
     Thus, it would be desirable to provide the wireless telecommunications industry with a vault to house micro-cells underground that is considerably smaller in size without sacrificing strength or security, and which maintains proper climate control for equipment longevity without cost or aesthetically prohibitive heat exchangers. 
     SUMMARY OF THE INVENTION 
     The present invention is directed to an improved vault or cabinet for storage of electronic equipment, such as wireless telecommunications equipment, underground in public right of ways. In a particularly innovative aspect of the invention, the micro-cabinet of the present invention is formed of a metal weldment, preferably stainless steel, which enables it to be made comparatively small without sacrificing strength or equipment security. Because of its reduced overall size, the micro-cabinet can easily be placed in a public right of way. 
     In another innovative aspect of the present invention, the micro-cabinet is substantially water-tight with a self contained cooling system and a water evacuation system. The water evacuation system preferably utilizes a one-way pressure actuated exhaust valve that enables the cabinet to be submerged in water with no danger to the enclosed equipment. Alternative cooling systems utilize similar one-way valves or snorkel-type piping running up an existing vertical structure along the public right of way. 
     In yet another innovative aspect of present invention, the micro-cabinet includes a weight or spring assisted rack for storage of transceiver equipment in the cabinet. The weight or spring assist system provides easy access to the stored electronic equipment when maintenance or repairs are necessary. In addition, the rack is preferably constructed to act as an internal support or brace for the micro-cabinet to further enhance the cabinet&#39;s overall structural integrity. 
     In a further innovation aspect of present invention, the micro-cabinet is preferably buried in a public right of way adjacent an existing vertical structure such as a light standard or sign. Cabling runs from the transceiver circuitry within the cabinet up along the interior or exterior of the vertical structure to an antenna positioned on top of the vertical structure. Unlike conventional designs, the vault or micro-cabinet of the present invention can be placed in virtually any city, under any existing vertical structure, e.g., a light standard, which is mounted on or near a sidewalk, while being fully disguised, and tending to pose no hazards to pedestrians. 
     In yet another innovative aspect, a cooling system of the present invention tends to eliminate the need for an electric powered air conditioner and dehumidifier, which tends to significantly reduce costs and advantageously enables the micro-cabinet to be dramatically smaller than most other telecommunication vaults. The cooling system of the present invention also advantageously enables a generator to be placed within the micro-cabinet, which ordinarily would be infeasible due to the cooling requirements of the generator. 
     In a preferred embodiment, the cooling system comprises a separate compartment attached to the end of the micro-cabinet, sharing a common wall. An opening or cooling vent is positioned toward the top of the common wall to allow hot air and moisture to vent from the micro-cabinet to the separate compartment. The separate compartment has air vents on the top, exposed to surface air, and louvered so that rain or water entering the separate compartment cannot fall through the opening in the common wall. These air vents allow heat and moisture to escape from the vault. A closure system comprising a door and a flotation device is provided to seal the cooling vent in the common wall. The door is mounted in moveable relation to the common wall and the flotation device, which causes the door to rise and seal the cooling vent as water fills the separate compartment, is operably coupled to the door. 
     Other innovative aspects of the invention include the preceding aspects individually or in combination. 
     Other aspects and features of the present invention will become apparent from consideration of the following description taken in conjunction with the accompanying drawings. 
    
    
     BRIEF DESCRIPTION OF THE DRAWINGS 
     FIG. 1 Element number  30  has been added to FIG. 1. A marked version of FIG. 1 is attached with the amended portion appearing in red. 
     FIG. 2 is a plan view of the micro-cabinet shown in FIG. 1 with a rack of the present invention shown in a down position. 
     FIG. 3 is a plan view of the micro-cabinet with the rack shown in a raised position. 
     FIG. 4 is a detail view of an exhaust valve of the present invention. 
     FIG. 5 is a plan view of an antenna site utilizing the micro-cabinet showing a cooling system alternative embodiment. 
     FIG. 6 is an end view of the micro-cabinet showing a cooling system alternative embodiment. 
     FIG. 7 is a plan view of an antenna site utilizing the vault of the present invention. 
     FIG. 8 a  and  8   b  are plan views of the micro-cabinet showing a cooling system alternative embodiment. 
     FIG. 9 Element number  313   b  on the left side of FIG. 9 has been changed to  313   a.  A marked version of FIG. 9 is attached with the amended portion appearing in red. 
     FIG. 10 is a top and partial sectional view of the micro-cabinet in FIG. 8 a  taken along line  10 — 10 . 
     FIG. 11 is a top view of the micro-cabinet showing a cooling system alternative embodiment. 
    
    
     DETAILED DESCRIPTION OF PREFERRED EMBODIMENTS 
     Referring to FIG. 1, a micro-cabinet or vault  10  of the present invention is shown. The micro-cabinet  10  includes an enclosure  12  that is preferably formed as a metal weldment. In a preferred embodiment, the enclosure  12  is a stainless steel weldment. Use of a metal, such as stainless steel, advantageously allows the surrounding earth to aid in the dissipation of heat from the micro-cabinet  10  and, also, advantageously enables the micro-cabinet  10  to be smaller, without sacrificing strength or equipment security. The enclosure is preferably about two (2) feet wide by three (3) feet long by four (4) feet deep, which is extremely small when compared to conventional underground vaults, and, depending on the transceiver configuration of the unit, the cabinet may vary between two (2) and five (5) feet in length. As a result, the micro-cabinet  10  can advantageously be placed next to or under vertical structures, such as a light standard, in existing public rights of way. 
     The enclosure  12  includes first and second side plates  13   a  and  13   b,  first and second end plates  14   a  and  14   b,  a bottom plate  15 , and a top plate  16 , which are preferably welded together. The top plate  16  includes an equipment access opening through which equipment can be loaded into the cabinet  10  or accessed for repair and maintenance. The opening is closeable by a hatch door  17 . The hatch  17  includes a handle  19 , a releasably lockable hinge or shock absorber-type hinge to maintain the hatch  17  in a generally vertical position, a security locking system, and a magnetic seal similar to those used on refrigeration units. The micro-cabinet  10 , with its metal enclosure  12  and watertight sealable hatch  17 , tends to be more watertight than conventional units, and, unlike the concrete walls of conventional vaults, the stainless steel walls of the present invention tend to minimize condensation. 
     Referring to FIGS. 1-3, the micro-cabinet  10  of the present invention preferably includes a weight assisted rack  20  mounted inside the enclosure  12  to place telecommunications equipment in the enclosure  12  and to allow easy access by maintenance personnel when repairs are needed. The rack  20  includes four (4) generally vertically positioned posts  21  and eight (8) top  22  and bottom  23  cross members. The posts  21  and cross-members  22  and  23  are preferably sized such that the outer extremities of the rack  20  are positioned closely adjacent to the inner walls of the cabinet  10 . In such a configuration, the rack  20  tends to provide additional support to the micro-cabinet  10 . As a result, the overall structural integrity of the micro-vault  10  is enhanced without the need to add separate internal supports or bracing. 
     The rack preferably includes four pulley systems  24  mounted in the enclosure  12  adjacent to the top and side plates  16  and  13 i a-b. Cables  26  pass through the pulleys and attach at opposing ends to a bottom cross member  23  and a weight  25 . The weights  25  are of sufficient weight to cause a fully loaded unrestrained rack  20  to rise out of the enclosure  12  as shown in FIG.  3 . The weights  25  are preferably 25 to 50 pounds heavier than a fully loaded rack  20 , thus requiring a maintenance worker to apply 25 to 50 pounds of offset downward force to position the rack  20  and electronic equipment in the enclosure  12 . Hooks or brackets (not shown) are preferably used to maintain the rack  20  in a down position as shown in FIG.  2 . 
     In an alternative embodiment, the pulley and weight system is replaced by springs. The springs are of sufficient strength such that a fully loaded unrestrained rack  20  is caused to rise out of the enclosure  12 . An offset force of 25 to 50 pounds is necessary to reposition the rack  20  in the enclosure  12 . 
     Referring to FIGS. 1 and 4, the micro-cabinet  10  of the present invention includes a novel water evacuation system  30  which is capable of venting any pooled water from the cabinet  10 . The evacuation system  30  includes a float-type sump pump  32  located in the bottom of the cabinet  10 . A pipe  33  extends from the pump  32  to exhaust valves  34  mounted to the top plate  16  of the cabinet  10 . The exhaust valve  34  is a commonly known one-way, pressure-type check valve. The one-way valve  34  tends to enable the vault  10  to actually be submerged underwater (a concern to carriers) with no leakage of water into the cabinet  10  and, thus, no danger to the equipment inside. 
     The valve  34 , as shown in detail in FIG. 4, is preferably mounted within a recess  38  formed in the top plate  16  of the cabinet  10  such that the valve-seat  35  of the valve  34  is flush with the base of the recess  38 . A valve cap  36  is slidable attached to the valve body  31 . The cap  36  includes slide posts  37  that are fixedly attached to the cap  36  and slidably received in stops formed on the interior of the valve body  31 . In operation, the cap  35  is forced upwardly by the pressure of the water flowing through the pipe  33 . The water exhausts through the holes formed between the slide posts  37 . The slide posts  37  are preferably formed of a predetermined length to ensure that the cap  35  is raiseable no further than to a position where it is flush with the top surface of the top plate  16  of the cabinet  10 . Optionally, the recess  38  may be covered with a perforated grate  39 . Because the cabinet&#39;s  10  top surface tends to be smooth or free of protruding parts, the cabinet  10  can be freely placed in and under public right of ways without tending to pose a hazard to pedestrians. 
     Although the construction of the micro-cabinet  10  advantageously allows the surrounding earth to aid in the dissipation of heat from the cabinet  10 , this cooling effect may be insufficient in certain climate conditions or as a result of equipment power consumption. A reduction in humidity or condensation within the cabinet may also be desirable for increased component life even when the temperature within the cabinet is being maintained at a desirable level, i.e., at or below about 100° Fahrenheit. To accommodate these potential cooling requirements, the micro-cabinet, as shown in FIG. 1, includes a self contained air conditioning unit  40 , such as a Model CR23 air conditioner manufactured by Hoffman, which cools and re-circulates the air within the cabinet  10  without needing to draw in air from the exterior of the cabinet  10 . The air conditioner  40 , which is shown mounted internally on end wall  14   a,  includes a low profile heat exchanger  41  mounted external to the micro-cabinet  10 . A protective vent cage  42  is constructed about the heat the exchanger  41  and is attached to the end  14   a  of the cabinet  10 . The cage  42  is formed of metal plating similar to the cabinet  10  with a perforated grate  44  covering the top of the cage  42  to allow air or water to circulate into the cage  42  to cool the heat exchanger  41 . The bottom of the cage  42  includes several holes  43  formed therein to allow condensation and water to weep. The upper portion of the cage  42 , above the heat exchanger  41 , may optionally include a filter-type material that is permeable to water and air and semi-permeable to dirt and debris. Inclusion of such material will tend to keep the heat exchanger  41  clean and working more efficiently. 
     Alternatively, as shown in FIG. 5, the micro-cabinet  10  of the present invention includes a cooling system that utilizes a pump  140  to draw cool air into the cabinet  10  and exhaust hot air out of the cabinet through a pair of vent pipes  141  and  142 . The vent pipes would preferable extend along the interior or exterior of an existing light standard or sign pole  50 . The ends of the vent pipes  141  and  142  are preferably bent over or hooded to prevent rain from entering the pipes and, thus, the cabinet  10 . 
     Another alternative cooling system  240  for the cabinet  10  of the present invention, as shown in FIG. 6, may utilize pop-up valves  234  and  235 , which are similar to the exhaust valves  34  of the water evacuation system  30  shown in FIGS. 1 and 4. An exhaust valve  234  of the cooling system  240 . is preferably a one-way, pressure-type pop up valve like valve  34 . However, an intake valve  235  is preferably a one-way, normally closed, solenoid-operated pop up valve. Like valve  34 , the valves  234  and  235  of this alternative cooling system  240  are preferably mounted in recesses  238  formed in the top plate  16  and preferably pop-up flush with or below the top surface of the top plate  16 . In operation, the solenoid-operate intake valve  235  is caused to open when the air condition unit or air pump  241  is activated. The pressure of the exhausting air will cause the exhaust valve  234  to open. 
     In operation, the micro-cabinet  10  of the present invention is preferably buried, as shown in FIG. 7, in a public right of way  60  adjacent an existing vertical structure  50  such as a light standard or sign. Cabling  70  runs from the transceiver circuitry within the enclosure  12  up along the interior or exterior of the vertical structure  50  to an antenna  80  positioned on top of the vertical structure  50 . The transceiver equipment is used to transmit and receive signals in a manner understood by those of skill in the art. 
     Turning to FIGS. 8 a,    8   b,    9  and  10 , an alternative embodiment of the micro-cabinet  10  of the present invention is shown. The micro-cabinet  10  includes a cooling system  300  that preferably comprises a separate cooling compartment  310  attached to the end of the micro-cabinet  10 , sharing a common wall  14   b.  As in previous embodiments, the micro-cabinet  10  includes an enclosure  12  comprising first and second side panels  13   a  and  13   b,  first and second end panels  14   a  and  14   b,  a bottom panel  15 , and a top panel  16 , which are preferably welded together or sealingly interconnected. The top panel  16  preferably includes an equipment access opening (not shown) through which equipment can be loaded into the cabinet  10  or accessed for repair and maintenance. The opening is closeable by a hatch door (not shown). 
     The cooling compartment  310  comprises a top panel  316 , a bottom panel  315 , an end panel  314 , first and second side panels  313   a  and  313   b,  and the common wall  14   b.  An opening or cooling vent  318  is positioned toward the top of the common wall  14   b  to allow hot air and moisture to vent from the micro-cabinet  10  to the cooling compartment  310 . The cooling compartment  310  has air vents  317  in the top panel  316 , exposed to surface air. The air vents  317 , which allow heat and moisture to escape from the vault  10 , may comprise a series of holes or, as shown in FIG. 10, a series of slots  317 . In either instance, the vents  317  are preferably louvered so that rain or water entering the cooling compartment  310  cannot fall through the opening  318  in the common wall  14   b.    
     Should rain or other water enter the interior  311  of the cooling compartment  310  such that it rises to the level of the cooling vent  318 , a closure system  320  is provided to seal the cooling vent  318 . The closure system  320  preferably comprises a door  321  and a flotation device  322 . The door  321  is mounted in moveable relation with the common wall  14   b  and is adapted to seal the cooling vent  318  in the common wall  14   b.  As shown in FIGS. 9 and 10, the door  321  is slidably mounted within a pair of opposing tracks  322   a  and  322   b.  The tracks  322   a  and  322   b  are mounted on the common wall  14   b  and run vertically adjacent to the sides of the cooling vent  318  in the common wall  14   b.  The tracks  322   a  and  322   b  preferably extend from the top of the cooling vent opening  318  toward the bottom panel  315  of the cooling compartment  310  beyond the bottom of the opening  318 . As shown in FIGS. 8 a  and  8   b,  the door  321  slides or travels up from the bottom panel  315  of the cooling compartment  310  to completely seal the opening  318  in the common wall  14   b.    
     The flotation device  323  comprises a floatable pad attached to the door  321  on the inside of the cooling compartment  310 . Preferably, the pad  323  is formed from Styrofoam, but may be formed from other suitable material or may comprise an inflatable bladder. The pad  323  is substantially the same height and width as the door  321  and approximately one-inch thick, and preferably has a buoyancy value sufficient to raise the door  321  as water fill Is the compartment  310 . To increase the surface area and, thus, the buoyancy of the pad  323 , a series of channels or cutouts  323  are formed in the pad  323 . If water floods the cooling compartment  310 , the door  321  simultaneous rises as the water level rises in the interior  311  of the cooling compartment  310 . With the aid of the water forcing the door  321  against the common wall  14   b,  the door  321  forms a water tight seal between the micro-cabinet  10  and the cooling compartment  310 . However, in the absence of rain or flooding, the door  321  is open, allowing venting of heat and moisture from the micro-cabinet  10 . 
     In an alternative embodiment, the closure mechanism  320  may include a float and pulley system (not shown) adapted to raise the door  321  as the water level in the cooling compartment  310  rises. Also, a gasket or the like may be positioned between the door  321  and the common wall  14   b  to further facilitate a water tight seal between the micro-cabinet  10  and the cooling compartment  310 . 
     In yet a further alternative embodiment, the cooling system  400  of the present invention may comprise two or more closure mechanisms  420  mounted in the cooling compartment  410  and adapted to seal two or more cooling vents  418   a  and  418   b  formed in the common wall  14   b  between the micro-cabinet  10  and the cooling compartment  410 . A multi-closure design tends to facilitate cooling without sacrificing effective sealing with larger sized micro-cabinets  10 . 
     With this cooling system  300  or  400 , weep holes (not shown) can be placed in the bottom of the vault or micro-cabinet  10  so that moisture or minute amounts or water may drain from the micro-cabinet  10 . However, any moisture that is absorbed through the weep holes can evaporate through the cooling system  300  or  400 . If excessive moisture is absorbed through the weep holes, a water pump, as discussed above, may be provided. 
     Unlike conventional designs, the vault or micro-cabinet  10  of the present invention can be placed in virtually any city, under any existing vertical structure, e.g., a light standard, which is mounted on or near a sidewalk, while being fully disguised, and tending to pose no hazards to pedestrians, who might otherwise trip on an exposed unit. 
     While the invention is susceptible to various modifications and alternative forms, a specific example thereof has been shown in the drawings and is herein described in detail. It should be understood, however, that the invention is not to be limited to the particular form disclosed, but to the contrary, the invention is to cover all modifications, equivalents, and alternatives falling within the spirit and scope of the appended claims.