Abstract:
A column air handling system includes a coil unit having a set of coils for changing a temperature of an air stream flowing therethrough and a fan unit for driving the air stream through the coil unit. The fan unit includes a plenum fan directly driven by a motor.

Description:
CROSS-REFERENCE TO RELATED APPLICATION 
       [0001]    The present application claims the benefit of U.S. Provisional Patent Application Ser. No. 60/850,549, filed Oct. 10, 2006. 
     
    
     FIELD OF INVENTION 
       [0002]    The present invention relates in general to air conditioning and heating techniques, and in particular to reduced noise air conditioning and heating systems. 
       BACKGROUND OF INVENTION 
       [0003]    Air conditioning and heating systems, including column air handling units, are known in the art. However, existing column air handling units are subject to a number of significant disadvantages. 
         [0004]    For example, the column air handling units disclosed in U.S. Pat. No. 6,402,612 and U.S. Pat. No. 6,267,665 utilize vane-axial fans, which operate at high speed and high pressure and hence generate a substantial amount of noise, which force the use of inlet and outlet silencers, such as cones, to make the generated noise level acceptable. Additionally, these systems utilize a high pressure design known as static regain that requires a series of hand manufactured tunnels and cones to enhance fan performance, which make the systems unnecessarily large and more expensive. Furthermore, the primary coils are provided on two opposing sides of the system, thereby requiring a larger space for installation. Finally, the fan is elevated high in the system which requires extensive field labor during installation, particularly if the fan is shipped uninstalled. 
         [0005]    Due to these significant disadvantages of the prior art, among others, improved column air, air conditioning and heating systems are needed, which are quiet, compact, and easy to install. 
       SUMMARY OF INVENTION 
       [0006]    According to one embodiment of the principles of the present invention, a column air handling system is disclosed that includes a coil unit including a set of coils for changing a temperature of an air stream flowing therethrough and a fan unit for driving the air stream through the coil unit. The fan unit includes a plenum fan directly driven by a motor. 
         [0007]    The use of a plenum fan and direct drive motor advantageously reduces the amount of noise generated by the column air handling system; particularly in view of prior art vane-axial fan systems. 
         [0008]    Additional embodiments of the principles of the present invention include a fan assembly, which includes the plenum fan and the direct drive motor and which is extendable from a given side of the fan unit. Preferably, the extendable fan unit is disposed low in the column unit (e.g. just above a base unit that allows the column air handling system to discharge air under a raised floor), such that the plenum fan and direct drive motor are easily accessible for replacement or servicing. 
     
    
     
       BRIEF DESCRIPTION OF DRAWINGS 
         [0009]    For a more complete understanding of the present invention, and the advantages thereof, reference is now made to the following descriptions taken in conjunction with the accompanying drawings, in which: 
           [0010]      FIG. 1  is a diagram of a representative column air conditioning/heating unit embodying the principles of the present invention; 
           [0011]      FIGS. 2A-2E  are a series of more detailed diagrams of the column air conditioning/heating unit of  FIG. 1 ; and 
           [0012]      FIGS. 3A-3E  are a series of more detailed diagrams of the quick release connector shown in  FIG. 1 . 
       
    
    
     DETAILED DESCRIPTION OF THE INVENTION 
       [0013]    The principles of the present invention and their advantages are best understood by referring to the illustrated embodiment depicted in  FIGS. 1-3  of the drawings, in which like numbers designate like parts. 
         [0014]      FIG. 1  is a diagram illustrating a typical application of a column air conditioning/heating unit  100  embodying the principles of the present invention. As shown in  FIG. 1 , air conditioning/heating unit  100  is vertically disposed between concrete slabs  101   a - 101   b , which are, for example, floors of a multiple floor building. Air conditioning/heating unit  100  is disposed in a space between a pair of horizontally spaced walls  102   a  and  102   b.    
         [0015]    A representative room is defined by wall  102   b , a raised floor  103 , and an internal ceiling  104 . Outside air is provided to conditioning/heating unit  100  from a pre-treatment unit outside the room through a conduit  105  disposed in the space between concrete slab  101   a  and internal ceiling  104 . 
         [0016]    As shown in  FIG. 1 , primary coils  108   a  and  108   b  are located on adjacent sides of air conditioning/heating unit  100 , which allows air conditioning/heating unit  100  to be installed into a corner and those require less floor space. (In  FIG. 1 , filters  206  have been removed to expose coils  108   a - 108   b , which are shown on the front and left sides of conditioning/heating unit  100 ). Primary coils  108   a - 108   b  may circulate chilled water, synthetic coolant (e.g. Freon), hot water, or steam. A bypass damper  109 , on the right side of air conditioning/heating unit  100 , allows return air to bypass coils  108   a  and  108   b . (Bypass damper  109  is associated with an additional filter on the right side of air conditioning/heating unit  100 ). In alternate embodiments, coils  108   a - 108   b  may be stacked on a single side of air conditioning/heating unit  100 . 
         [0017]    During cooling operation, air conditioning/heating unit  100  pulls return air flow through the space between floor  101   a  and internal ceiling  104 . Some of the return air, typically at approximately 75 degrees Fahrenheit, passes across coils  108   a - 108 , and is cooled to typically about 50 degrees Fahrenheit. The rest of the return air flows directly through bypass damper  109  without additional cooling. The cooled air flowing across coils  108   a - 108   b  and the air flowing through bypass damper  109 , is mixed with the outside air provided through conduit  105 , which typically has been cooled to approximately 55 degrees Fahrenheit. The resulting discharge air is typically at approximately 60 to 65 degrees Fahrenheit. 
         [0018]    Air conditioning/heating unit  100  then discharges the cooled and filtered air into the space between concrete slab  101   b  and raised floor  103 . The discharge air flow passes through raised floor  103  through a set of air diffusers  106 . Pressure monitors  107  monitors the discharge air pressure within the space between raised floor  103  and concrete slab  101   b.    
         [0019]      FIGS. 2A-2D  are a series of more detailed views of air conditioning/heating unit  100 . As shown in  FIGS. 2A and 2B , the primary components of air conditioning/heating unit  100  include elbow section  200 , which receives outside air from conduit  105  of  FIG. 1 . Coil and filter section  201  includes the filters for filtering return air flow intake, as well as coils  108   a  and  108   b  for cooling or heating that air. Variable frequency drive section  202  passes air pulled by fan section  203 , and supports electronic controls for varying the motor speed and for disconnecting air conditioning/heating unit  100 , when required. 
         [0020]    In the illustrated embodiment, coils and filter section  201 , variable frequency drive section  202 , and fan unit  203  have a rectangular construction, which generally includes a metallic frame and metal sidewalls, along with apertures as required for supporting structures such as the filters, elbow  200 , and access doors. Depending on the application, number, sizes, and shapes of the units making up air conditioning/heating unit  100  may vary. 
         [0021]    Independent support section  205  maintains air cooling unit  100  above the associated supporting structure (e.g. concrete slab  101   b  in  FIG. 1 ) and includes a pyramid-shaped deflector  223  that discharges air outward from fan assembly  204  in all directions. Support section  205  varies in height from embodiment to embodiment, depending on the exact height of floor  103 , and may range in height, for example, from 8″ to 48″. Advantageously, independent support section  205  allows for access flooring and flashing to be installed before the installation of the remainder of air conditioning/heating unit  100 . This feature significantly reduces the amount of field labor required during the installation of air conditioning/heating unit  100 . 
         [0022]    As shown in  FIG. 2C , coil and filter section  201  includes a set of service filters  206  for filtering return air. In some embodiments, coil and filter section  201  may include electrical heating elements. In the illustrated embodiment, primary coils are selected to operate at an approximate flow rate 300 FPM (feet per minute) to minimize moisture delivery in the discharge air flow. 
         [0023]    A pair of connectors  207  allows the cooling or heating fluid to be cycled through the internal cooling coils. Drain pan connection  208  provides for the removal of condensate extracted from the return air by the coils. 
         [0024]    Variable frequency drive section  202  includes drive motor control  209  and a lockable disconnect control switch  210 . Drive motor controls  209  allows the speed of the direct drive motor of fan unit  201 , discussed in detail below. In the overall system shown in  FIG. 1 , drive controls  209  receive electronic feedback from pressure sensors  107  and adjust the motor speed as appropriate to main the appropriate air pressure in the space between concrete slab  107  and raised floor  103 . 
         [0025]    The frame of fan unit  203  includes tracks which support fan assembly  204 . Advantageously, fan assembly  204  is located just above the floor and rolls into and out on casters on the front and rear edges of the top of the assembly frame, as discussed further below in conjunction with  FIG. 2E . In  FIG. 2C , fan assembly  204  is shown on a dolly  213 , which allows it to be rolled to fan unit  203  and the casters engaged with the corresponding tracks. Preferably dolly  213  includes a manual hydraulic lifting device that allows fan assembly  204  to be easily mated with the support structures of fan unit  203 . (Fan assembly  204  can be completely or partially rolled-out on track extensions, as needed for installation, replacement, or servicing.) 
         [0026]    Fan assembly  204  includes a quite plenum fan with direct drive motor assembly  212  and fan dolly  213 . Removable doors  214  provide access to fan assembly  204 , within metal casing  215 . Removable doors  214  also allow access to the drain pan within coil and filter section  201  for cleaning purposes. A quick release flexible connector  110 , shown in  FIG. 1 , allows fan assembly  204  to be released from the frame of fan unit  203 . 
         [0027]      FIGS. 2D-2E  illustrate fan assembly  204  in further detail. In particular, fan assembly  204  includes a direct drive motor  216  and fan  217 . Direct drive motor  216  is supported by motor frame  216 . Rolling frame  211  is generally formed by tubular members  219  and includes casters  220  and isolators  221 . The fan plenum extends through an apron  222 . 
         [0028]    In the illustrated embodiment, direct drive motor  216  is a nominally rate 900 RPM, (rotations per minute) 10 HP (horsepower) motor operating from a three-phase, 460 volt, 60 Hz power source. In alternate embodiments, drive motor  216  may have a higher rated speed, for example 1200 RPM, although preferably the rated speed is kept below the typical rated 1700 RPM speed used in conventional high pressure/high velocity vane-axial systems, to reduce noise and vibration. During typical operation of the illustrated embodiment (i.e. with a 900 RPM motor) motor controls  209  maintain the speed of motor  216  within the approximate range of 400 to 700 RPM. 
         [0029]    Advantageously, quite plenum fan  217  does not require inlet or outlet silencers or an inlet cone. The size of quite plenum fan  217  will vary depending on the application of air handling system  100  and may provide, for example, flow rates of between 1000 to 25,000 CFM (cubic feet per minute). 
         [0030]      FIGS. 3A-3E  are a series of view of quick release connector  110  shown in  FIG. 1 , with  FIG. 3A  showing an alternate configuration of air conditioning/heating unit  100 /Advantageously, quick release connector  110  allows fan assembly  204  to be quickly and easily released from fan unit  203 . 
         [0031]    As shown in  FIG. 3B , quick release connector  110  wraps around the upper edge  310  of plenum fan  217 . Spring steel strips  311  are sewn along the upper and lower edges of the flexible material of quick release connector  110 . One end of quick connect connector  110  includes a small section  312  of female industrial Velcro and the opposing end includes a small corresponding section  313  of male industrial Velcro. As shown in  FIGS. 3C and 3E , a pair of quick release latches  314  is also provided. 
         [0032]    During use, as shown in  FIG. 3E , spring steel strips  311 , Velcro sections  312  and  313 , and quick release latches  314  ensure that quick release connector  110  maintains a snug fit around edge  310  of plenum fan  217 . Advantageously, the leakage of heated or cooled air being pulled by fan unit  213  is minimized. 
         [0033]    Although the invention has been described with reference to specific embodiments, these descriptions are not meant to be construed in a limiting sense. Various modifications of the disclosed embodiments, as well as alternative embodiments of the invention, will become apparent to persons skilled in the art upon reference to the description of the invention. It should be appreciated by those skilled in the art that the conception and the specific embodiment disclosed might be readily utilized as a basis for modifying or designing other structures for carrying out the same purposes of the present invention. It should also be realized by those skilled in the art that such equivalent constructions do not depart from the spirit and scope of the invention as set forth in the appended claims. 
         [0034]    It is therefore contemplated that the claims will cover any such modifications or embodiments that fall within the true scope of the invention.