Abstract:
A housing cooperates with an air mover rotating about a rotation axis to move air received from an approach to an exhaust. The approach is generally oriented about a direction intersecting the housing at upstream and downstream limits. The housing presents an interior surface establishing radii between the axis and the surface. The radii have a generally constant radial value across a width in planes containing the axis in a first zone between the downstream limit and a first locus, and in a second zone between a second locus and the exhaust. The radii vary between a smallest and a largest radius across the width in planes containing the axis in a variance zone upstream of the axis. The smallest radius is less than the radial value at the first and second loci. The largest radius is larger than the radial value at one of the first and second loci.

Description:
BACKGROUND OF THE INVENTION  
       [0001]     The present invention is directed to air moving or air handling units, and especially to air handling devices in which blower housing apparatuses are contained, such as in an HVAC (Heating Ventilating Air Conditioning) system.  
         [0002]     Air handling units for HVAC systems are typically constrained in their physical dimensions to conform with predetermined industry standards. The relevant industry standards are predicated, at least in part, upon a requirement that some components of HVAC systems must be amenable to installation in a residential attic, closet or other restricted space. Such space-restricted components must, therefore, be restricted to a particular “footprint” and be passable through an access opening to the attic, closet or other restricted space. Space utilization within such components is therefore a constraint in their design. Air handling units for use in a residential HVAC system are, by way of example and not by way of limitation, among such components.  
         [0003]     Typical air handling units include an evaporator unit and a blower unit. In some air handling units if a blower unit is placed too close to an associated evaporator unit a problem is created because condensate can be entrained in high velocity air flow from the evaporator unit through the blower unit and cause water damage in the space served by the HVAC system, such as a home or an office. A contributing factor to this problem is the typical bluff shape presented by the housing containing the blower unit to approaching air from the evaporator unit. The bluff shape restricts the air flow channel as the air flows from the evaporator, between the blower housing and a surrounding cabinet, through the blower unit and to the exhaust area of the air handling unit. Such a restricting of air flow area increases speed of the air flow and thereby permits entrained moisture to be carried through the air handling unit to the area being serviced by the HVAC system. As a result of these factors, blower housings are typically placed a separation distance from evaporator units to permit entrained moisture to fall out of air before the air enters the blower unit. Such a design occupies space unnecessarily. Further, the restricted air flow required by such designs contributes to lower static pressure performance and lower efficiency.  
         [0004]     There is a need for a design for an air handling unit that occupies no greater “footprint” than presently dictated by industry standards, that still passes through predetermined openings such as openings accessing attics, closets or other restricted spaces, and that permits freer air flow to enhance static pressure performance and efficiency without entraining moisture in flowing air provided to a serviced area.  
       SUMMARY OF THE INVENTION  
       [0005]     A housing cooperates with an air mover rotating about a rotation axis to move air received from an approach to an exhaust. The approach is generally oriented about an axis intersecting the housing at upstream and downstream limits. The housing presents an interior surface establishing radii between the axis and the surface. The radii have a generally constant radial value across a width in planes containing the axis in a first zone between the downstream limit and a first surface locus, and in a second zone between a second surface locus and the exhaust. The radii vary between a smallest and a largest radius across the width in planes containing the axis in a variance zone upstream of the axis. The smallest radius is less than the radial value at the first and second surface loci. The largest radius is larger than the radial value at at least one of the first and second surface loci.  
         [0006]     It is, therefore, an object of the present invention to provide an air handling unit that occupies no greater “footprint” than presently dictated by industry standards, that still passes through predetermined openings such as openings accessing attics, closets or other restricted spaces, and that permits freer air flow to enhance static pressure performance and efficiency without entraining moisture in flowing air to a serviced area Further objects and features of the present invention will be apparent from the following specification and claims when considered in connection with the accompanying drawings, in which like elements are labeled using like reference numerals in the various figures, illustrating the preferred embodiments of the invention.  
     
    
     BRIEF DESCRIPTION OF THE DRAWINGS  
       [0007]      FIG. 1  is a schematic diagram of representative air handling equipment in which the present invention may be advantageously employed.  
         [0008]      FIG. 2  is a side view of an air handling unit employing the teachings of the present invention.  
         [0009]      FIG. 3  is a bottom view of the air handling unit illustrated in  FIG. 2  taken in direction  3 - 3  in  FIG. 2 . 
     
    
     DETAILED DESCRIPTION OF THE PREFERRED EMBODIMENT  
       [0010]     The term “locus” is intended herein to indicate a place, location, locality, locale, point, position, site, spot, volume, juncture, junction or other identifiable location-related zone in one or more dimensions. A locus in a physical apparatus may include, by way of example and not by way of limitation, a corner, intersection, curve, line, area, plane, volume or a portion of any of those features. A locus in an electrical apparatus may include, by way of example and not by way of limitation, a terminal, wire, circuit, circuit trace, circuit board, wiring board, pin, connector, component, collection of components, sub-component or other identifiable location-related area in one or more dimensions.  
         [0011]      FIG. 1  is a schematic diagram of representative air handling equipment in which the present invention may be advantageously employed. In  FIG. 1 , a representative residential air handling unit  10  is of the sort of air handling unit appropriate, by way of example and not by way of limitation, for use with a heat pump HVAC system. Air handling unit  10  is enclosed in a cabinet  12  and includes an evaporator device  14  and an air handling device or blower device  16 . Evaporator device  14  and blower device  16  are situated generally symmetrically with respect to a flow axis  30 . An air filter  18  closes a first end  19  of cabinet  12 .  
         [0012]     Drain pans  20 ,  22  permit operation of air handling unit  10  with flow axis  30  oriented vertically with blower device  16  above evaporator device  14  or operation of air handling unit  10  in a horizontal orientation with flow axis  30  oriented horizontally.  
         [0013]     Evaporator device  14  includes a first evaporating panel  24  and a second evaporating panel  26 . Evaporating panels  24 ,  26  generally span drain pan  22  and are arranged generally in a “V” structure having an open end  27  generally spanning drain pan  20  and an apex  29  generally situated at flow axis  30 .  
         [0014]     Blower device  16  includes a housing  40  containing a fan  42 . Fan  42  rotates about an axis  32  and is substantially centered on flow axis  30 . Flow axis  30  intersects housing  40  at an upstream limit  44  and at a downstream limit  46 . Housing  40  has an exhaust locus  48  substantially spanning second end  21  of cabinet  12 . Housing  40  also has a first input locus  50  and a second input locus  52 . Input loci  50 ,  52  provide air passages generally centered on axis  32 . Fan  42  operates to draw air through air filter  18  in a flow or approach direction generally symmetrical with respect to flow axis  30 . As air encounters housing  40  generally at upstream limit  44  and across portions of housing  40  facing upstream toward first end  19 , air is routed between housing  40  and cabinet  12  to enter housing  40  through input loci  50 ,  52  in a flow direction generally parallel with axis  32 . Air flow may not reach exact parallelism with respect to axis  32 , but general parallelism with axis  32  is achieved until fan  42  redirects air outward from axis  32  in a radial flow direction generally perpendicular with axis  32  against the inner wall  41  of housing  40 .  
         [0015]     In order to facilitate understanding the present invention, air handling unit  10  is illustrated in  FIG. 1  representing housing  40  using prior art construction and using construction according to the teachings of the present invention. Prior art construction of housing  40  provided a bluff face  60  (indicated in dotted line format in  FIG. 1 ) so that a clearance gap Δ was established between housing  40  and cabinet  12 . Bluff face  60  typically was formed using a substantially rectangular cross-section, as indicated in  FIG. 1 , so that corners such as corner  62  generated turmoil in air flow past housing  40 , restricted air flow from evaporator device  14  to fan  42 . Such restriction of air flow increased air flow velocity in regions between housing  40  and cabinet  12  and adversely affected static pressure performance and efficiency of air handling unit  10 . Prior art construction required a minimum spacing between bluff face  60  and apex  29  to ensure moisture would not be entrained in air traversing blower device  16  to enter a space being serviced by an HVAC system employing air handling unit  10 . By way of example and not by way of limitation, a distance on the order of four inches was required between bluff face  60  and apex  29  to achieve the desired operating characteristics without undesired levels of entrained moisture in air traversing blower device  16 .  
         [0016]     It is preferred that housing  40  present an inner surface  41  with respect to axis  32  in a generally Archimedian or logarithmic scroll structure. It is known that larger volute expansion angles in such structures allow a blower wheel such as fan  42  to achieve higher static pressure for a given flow rate and that blower efficiency improves with increased expansion angle in the range of expansion angles employed in air moving units used with HVAC systems (generally, by way of example and not by way of limitation, expansion angles in the range of seven to fifteen degrees). Space constraints imposed by industry standards (discussed generally above) preclude simply providing larger expansion angles as a solution.  
         [0017]     The inventors have discovered that by providing a smoother face to approaching air by housing  40 , less turmoil is imparted to air flowing past housing  40  en route to input loci  50 ,  52  and less restriction of air flow between housing  40  and cabinet  12  is presented. A contoured face  61  is provided to establish a gradual transition of air flow from evaporator device  14  around housing  40  and into input loci  50 ,  52 . Also provided is a change to inner wall structure of housing  40  to present a revised inner surface  43 . Revised inner surface  43  establishes a variance zone  70  between a first zone-edge  72  and a second zone-edge  74 . It is preferred that variance zone  70  be substantially centered on flow axis  30 . It is further preferred that variance zone  70  include a smaller blunting zone  80  between a first blunting-zone-edge  82  and a second blunting-zone-edge  84 . It is preferred that blunting zone  80  be substantially centered on flow axis  30 .  
         [0018]     Variance zone  70  and blunting zone  80  cooperate to provide a clearance with cabinet  12  that is greater than clearance gap Δ provided by prior art bluff face  60 . Providing the outer profile necessary to accommodate variance zone  70  and blunting zone  80  also accommodates providing revised inner surface  43 . Revised inner surface  43  permits providing a larger volute expansion angle than may be provided by bluff face  60  and inner surface  41  in the same “footprint” area occupied by air handling unit  10 . Providing such a larger expansion angle at least between zone-edges  72 ,  74  allows fan  42  to achieve higher static pressure for a given flow rate and improved blower efficiency as compared with prior art bluff face  60  and inner surface  41 . Further details describing the improved structure of the present invention are provided below in connection with  FIG. 2 .  
         [0019]      FIG. 2  is a side view of an air handling unit employing the teachings of the present invention.  FIG. 3  is a bottom view of the air handling unit illustrated in  FIG. 2  taken in direction  3 - 3  in  FIG. 2 . Regarding  FIG. 2  and  FIG. 3  together, blower device  16  includes housing  40  containing fan  42 . Fan  42  rotates about axis  32  and is substantially centered on flow axis  30 . Flow axis  30  intersects housing  40  at an upstream limit  44  and at a downstream limit  46 . A plane  36  containing axis  32  and substantially perpendicular with axis  30  establishes housing intersection loci  100 ,  102  ( FIG. 2 ) and  100   a  ( FIG. 3 ). Another housing intersection locus is also established behind locus  102  ( FIG. 2 ) and behind locus  100   a  ( FIG. 3 ) but is not visible in  FIGS. 2 and 3 . Housing  40  includes exhaust locus  48  and input loci  50 ,  52 . Input loci  50 ,  52  provide air passages generally centered on axis  32 . Fan  42  operates to draw air in a flow or approach direction generally symmetrical with respect to flow axis  30 . As air encounters housing  40  generally at upstream limit  44  and across portions of housing  40  facing upstream, air is routed between housing  40  and cabinet  12  (not shown in  FIGS. 2 and 3 ; see  FIG. 1 ) to enter housing  40  through input loci  50 ,  52  in a flow direction generally parallel with axis  32 . Air flow may not reach exact parallelism with respect to axis  32 , but general parallelism with axis  32  is achieved until fan  42  redirects air outward from axis  32  in a radial flow direction generally perpendicular with axis  32  against inner wall  43  of housing  40 . In the exemplary blower unit  16  of  FIGS. 2 and 3 , fan  42  rotates about axis  32  in a rotation direction indicated by an arrow  33 .  
         [0020]     In order to facilitate understanding the present invention, blower device  16  is illustrated in  FIGS. 2 and 3  representing housing  40  using prior art construction and using construction according to the teachings of the present invention. Prior art construction of housing  40  provided a bluff face  60  (indicated in dotted line format) typically formed a substantially rectangular cross-section so that distance from axis  32  to interior surface  41  of prior art blower housing  40  (using bluff face  60 ) is a constant value r across the width W (see  FIG. 3 ) of blower housing  40  in planes containing axis  32 .  
         [0021]     The present invention provides interior surface  43  so that a plurality of radii R 1 , R 2 , R 3 , R 4 , R n  generally perpendicular with rotational axis  32  between axis  32  and interior surface  43  define inner surface  43  in planes containing axis  32  in variance zone  70  between zone-edges  72 ,  74 . An example of such a plane containing axis  32  is plane  71  ( FIG. 2 ). Still referring to  FIG. 2 , radii generally perpendicular with rotational axis  32  in planes containing axis  32  are substantially constant across width W between downstream limit  46  and a first housing locus or zone-edge  74 , and from a second housing locus or zone-edge  74   a  toward exhaust locus  48  in so far as the desired Archimedian or logarithmic scroll structure is maintained. Radial lengths will likely vary among various planes containing axis  32  that are outside variance zone  70  to establish the desired expansion angle for housing  40  with respect to fan  42 , as will be understood by those skilled in the art. It is preferred that zone edges  74 ,  74   a  be established generally in the vicinity of plane  36  that establishes housing intersection loci  100 ,  102  and other housing intersection loci not visible in  FIG. 2  , as described above. In the exemplary structure illustrated in  FIG. 2 , zone edges  74 ,  74   a  are established upstream of plane  36 .  
         [0022]     Thus, in  FIG. 3 , radii R n  have a relationship: R 1 &lt;R 2 &lt;R 3 &lt;R 4 &lt;R n . The portion of variance zone  70  between upstream limit  44  and second zone-edge  74  is preferably configured substantially as a mirror-image of the portion of variance zone  70  between first zone-edge  72  and upstream limit  44 . Some radii R n  are smaller than radius r, such as, by way of example and not by way of limitation, radii R 1 , R 2 . Other radii R n  are larger than radius r, such as, by way of example and not by way of limitation, radii R 3 , R 4 , R n . By this variable radii construction, a larger expansion angle may be provided for a portion of the flow zone within housing  40  from downstream limit  46 , through upstream limit  44  and toward exhaust locus  48 . Larger volute expansion angles in such structures allow a blower wheel such as fan  42  to achieve higher static pressure for a given flow rate and improve blower efficiency.  
         [0023]     It is preferred that variance zone  70  be substantially centered on flow axis  30 . It is further preferred that variance zone  70  include a smaller blunting zone  80  between a first blunting-zone-edge  82  and a second blunting-zone-edge  84 . It is preferred that blunting zone  80  be substantially centered on flow axis  30 .  
         [0024]     Variance zone  70  and blunting zone  80  cooperate to provide a clearance with cabinet  12  ( FIG. 1 ) that is greater than clearance gap Δ provided by prior art bluff face  60 . Providing the output profile necessary to accommodate variance zone  70  and blunting zone  80  also accommodates providing a larger volute expansion angle than may be provided by bluff face  60  and inner surface  41  and still fit in the available blower compartment space occupied by blower device  16 . Providing such a larger expansion angle at least between zone-edges  72 ,  74  ( FIG. 3 ) allows fan  42  to achieve higher static pressure for a given flow rate and improved blower efficiency as compared with prior art housing structures using bluff face  60  and inner surface  41 .  
         [0025]     It is to be understood that, while the detailed drawings and specific examples given describe preferred embodiments of the invention, they are for the purpose of illustration only, that the apparatus and method of the invention are not limited to the precise details and conditions disclosed and that various changes may be made therein without departing from the spirit of the invention which is defined by the following claims: