Patent Publication Number: US-2011061414-A1

Title: Rooftop mounted air conditioner

Description:
CROSS REFERENCE TO RELATED APPLICATION  
     This application claims priority to and the benefit of U.S. Provisional Patent Application Ser. No. 61/241,511 entitled “Rooftop Mounted Air Conditioner” filed on Sep. 11, 2009. The content of this application is incorporated herein by reference in its entirety. 
    
    
     FIELD OF THE INVENTION  
     This invention relates generally to rooftop mounted air conditioners for passenger transit vehicles and, more particularly, to a low profile arrangement within the passenger compartment for discharging supply air to and drawing return air from the passenger compartment. 
     BACKGROUND OF THE INVENTION 
     Air conditioning modules are commonly mounted to the rooftop of passenger transit vehicles, such as for example public and private passenger buses, school buses, people mover cars, mono-rail transit cars and the like, for conditioning the air within the passenger compartment of the vehicle. Rooftop mounted air conditioning modules are also mounted on the rooftops of recreational vehicles for conditioning the air within the housing compartment of the recreational vehicle. Rooftop air conditioning modules of this type include a condenser section and an evaporator section that are housed in separate areas of the module housing. The evaporator section is in airflow communication with the passenger compartment interior to the vehicle and the condenser section is in airflow communication with the environment exterior to the vehicle. 
     For example, U.S. Pat. No. 5,605,055 discloses a rooftop air conditioning module for a transit bus having a rooftop-mounted housing including a set of condenser coils disposed outboard of the evaporator section. The evaporator section includes a pair of longitudinally extending evaporator coils that are disposed on opposite sides of a central return air opening in the rooftop of the bus. A plurality of evaporator fans are associated with each of the evaporator coils for drawing air from the passenger compartment of the bus through the return air opening and thence passing a first portion through the first evaporator coil and a first supply air discharge opening back into the passenger compartment and a second portion through a second supply air discharge opening back into the passenger compartment. The first supply air discharge air opening is formed in the rooftop on one longitudinally extending side of the central return air opening and the second supply air discharge opening is formed in the rooftop on the opposite longitudinally extending side of the return air opening. 
     It is also known to mount a generally rectangular, toroidal-like housing to the ceiling side of the rooftop of the bus with the open center of the toroidal-like housing disposed about the return air opening. So positioned, the supply air discharge air openings open into the respective opposite sides of the toroidal-like housing for discharge therefrom through a plurality of outlets in the walls of the toroidal-like housing. The housing extends downwardly into the passenger compartment by several inches, typically from three to five inches. Due to the toroidal-like nature of the housing, the housing extends downwardly into the center aisle of the vehicle, consequently reducing the available headroom for passengers walking up or down the aisle. Since different bus designs have different roof contours, such one-piece generally rectangular toroidal-like housings typically are custom fit for a particular roof contour because of the relatively wide width of the housing, typically from 3½ to 4½ feet. Thus, these one-piece housing are generally not interchangeable between buses having different roof contours. Additionally, because these one-piece housings are typically from 3 to 6 feet in length, multiple technicians are required to mount the housing to the passenger compartment ceiling side of the bus roof, 
     SUMMARY OF THE INVENTION 
     An air conditioning system for a passenger transit vehicle includes a rooftop mounted air conditioning module that has a low profile airflow management arrangement on the passenger compartment side of the roof of the vehicle for discharging air from and returning air to the evaporator section on the exterior side of the rooftop of the vehicle. 
     An air conditioning system is provided for a transit vehicle having a passenger compartment having a rooftop extending longitudinally over the passenger compartment, with the rooftop having a first and a second laterally spaced supply air opening passing therethrough and a return air opening passing therethrough. The air conditioning system includes an air conditioning module disposed atop the rooftop of the vehicle in operative association with the first and second supply air openings whereby air from the passenger compartment passes through the return air opening into the air conditioning module and back into the passenger compartment through the first and second supply air openings, a first supply air discharge plenum housing disposed within the passenger compartment in juxtaposition with the first supply air opening, a second supply air discharge plenum housing disposed within the passenger compartment in juxtaposition with the second supply air opening; and a grille disposed in juxtaposition with the return air opening. The grille may be housed in a low profile frame disposed within the passenger compartment. In an embodiment, the return air grille and frame assembly has a depth extending into the passenger compartment that is less than the depth by which either of the first and second supply air discharge plenum housings extend into the passenger compartment. In an embodiment, the first and second supply air discharge plenum housings have a depth of less than about 3 inches, and the grille and frame assembly, which may be disposed centrally between the first and second supply air discharge openings, has a depth of less than about 1 inch. 
     Each of the first and second supply air discharge plenum housings may include a generally rectangular upper perimetral flange, a lower floor panel disposed in spaced relationship below the perimetral flange, a pair of longitudinally extending side walls depending from opposite longitudinal sides of the perimetral flange to opposite longitudinal sides of the floor panel, and a pair of laterally extending side walls depending from opposite lateral sides of the perimetral flange to opposite lateral sides of the floor panel. In an embodiment, each of the side walls depends inwardly from the upper perimetral flange at an included angle of about 45 degrees. At least one of the floor panel and the side walls has at least one air outlet opening therein. In an embodiment, each of the floor panel and the side walls has at least one air outlet opening therein. In an embodiment, the first and second supply air discharge plenum housings are interchangeable. 
     In an aspect of the invention, a supply air discharge plenum arrangement is provided for a rooftop mounted air conditioning system for a passenger transit vehicle including a first supply air discharge plenum housing for disposition within the passenger compartment in juxtaposition with one of a first and second supply air openings, and a second supply air discharge plenum housing for disposition within the passenger compartment in juxtaposition with the other of the first and second supply air openings. The first and second supply air discharge plenum housings each have at least one air outlet provided therein. The first and second supply air discharge plenum housings are interchangeable. 
     In an aspect of the invention, an airflow management arrangement is provided for a rooftop mounted air conditioning system for a transit vehicle having a passenger compartment having a rooftop extending longitudinally over the passenger compartment, the rooftop having a first and a second laterally spaced supply air openings passing therethrough and a return air opening passing therethrough, the return air opening disposed centrally between the first and second laterally spaced supply air openings. The airflow management arrangement includes a first air supply discharge plenum housing, a second air supply discharge plenum housing, and a return air grille assembly. The first supply air discharge plenum housing is for disposition within the passenger compartment in juxtaposition with one of the first and second supply air openings. The second supply air discharge plenum housing is for disposition within the passenger compartment in juxtaposition with the other one of the first and second supply air openings. Each of the first and second supply air discharge plenum housings has at least one air outlet provided therein. The return air grille assembly has a grille for disposition in juxtaposition with the return air opening and has a low profile frame disposed within the passenger compartment. The grille assembly has a depth extending into the passenger compartment that is less than a depth by which either of the first and second supply air discharge plenum housings extends into the passenger compartment. 
    
    
     
       BRIEF DESCRIPTION OF THE DRAWINGS 
       For a further understanding of the disclosure, reference will be made to the following detailed description which is to be read in connection with the accompanying drawing, in which: 
         FIG. 1  is a perspective view of a passenger transit vehicle equipped with an air conditioning system having an air conditioning module mounted atop the roof thereof; 
         FIG. 2  is a plan view of the air conditioning module mounted atop the roof of a transit vehicle of  FIG. 1 ; 
         FIG. 3  is a side elevation view, partly in section, of the rooftop mounted air conditioning module of  FIG. 2 ; 
         FIG. 4  is a cross-sectional elevation view of the air conditioning module mounted on the rooftop of the transit vehicle as taken along line  4 - 4  of  FIG. 3 ; 
         FIG. 5  is a plan view looking upwardly from within the passenger compartment of the transit vehicle of the airflow ducting arrangement of the air conditioning module of  FIG. 4 ; 
         FIG. 6  is a perspective view of an exemplary embodiment of a supply air discharge plenum housing in accord with the invention; 
         FIG. 7  is a plan view of the exemplary embodiment of a supply air discharge plenum housing of  FIG. 6 ; 
         FIG. 8  is a side elevation view of the supply air discharge plenum housing of  FIG. 7  showing an exemplary embodiment of the longitudinally extending side walls thereof; and 
         FIG. 9  is an end elevation view of the supply air discharge plenum housing of  FIG. 7  showing an exemplary embodiment of the laterally extending end walls thereof. 
     
    
    
     DETAILED DESCRIPTION OF THE INVENTION 
     Referring initially to  FIGS. 1-3  of the drawing, there is depicted a passenger transit vehicle  200  equipped with an air conditioning system including an air conditioning module  100  mounted atop the roof  202  of a transit vehicle  200  having a passenger compartment beneath the roof  202 . The transit vehicle may be a bus, such as for example a school bus or public transportation bus, a people mover car, a mono-rail car or other passenger transit vehicle wherein it is desired to condition the air within the passenger compartment of the transit vehicle. 
     The air conditioning module  100  includes an evaporator module  120  and a condenser module  130  disposed within a longitudinally extending housing  110  mounted to the roof  202  of the transit vehicle  200 . In the depicted embodiment, the evaporator module  120  is disposed aft, that is toward the rear end of the transit vehicle  200 , of the condenser module  130 . However, it is to be understood that in another embodiment the condenser module  130  and the evaporator module  120  may be reversed, that is the evaporator module  120  may be disposed forward of the condenser module  130 . Further, in another embodiment, the condenser coils  132  may be disposed outboard of the evaporator coils  122 , such as in the aforementioned U.S. Pat. No. 5,605,055. The specific arrangement within the rooftop mounted air conditioning module  100  of the evaporator coils and the condenser coils relative to each other is not particularly germane to application of the supply air plenum arrangement and the airflow management arrangement disclosed herein and those skilled in the art will recognize that the supply air plenum arrangement and the airflow management arrangement disclosed herein may be applied to various designs of rooftop mounted air conditioning modules. 
     In the depicted embodiment, the condenser module  130  includes a pair of longitudinally extending condenser coils  132  and a pair of condenser fans or blowers  134  for moving outdoor air across the condenser coils  132  in heat exchange relationship with a refrigerant circulating through the condenser coils. It is to be understood, however, that the design of the condenser module  130  is not germane to the invention and that persons of ordinary skill in the art will recognize other arrangements of the condenser coils and the condenser fans that may be used in the air conditioning module  100 . The condenser module  130  is disposed in the forward region of the housing  110  and isolated from the passenger compartment  205  of the transit vehicle  200 . 
     The air conditioning system also includes a refrigerant vapor compressor (not shown) that may be housed, typically together with a prime mover (not shown) for driving the compressor, in a compartment  250  remotely from the roof top mounted air conditioning module  100 . Alternatively, the refrigeration compressor and its prime mover, for example an electric motor, may be housed within the condenser module  130 . The refrigeration compressor compresses refrigerant vapor and circulates the refrigerant through a conventional closed loop refrigeration cycle circuit that includes the condenser coils  132  and a set of evaporator coils  122  housed in the evaporator module  120 , 
     Referring now to  FIG. 4  in particular, the evaporator module  120  includes at least one evaporator fan  124  in operative association with the aforementioned set of evaporator coils  122 . The evaporator module  120  is isolated from the condenser module  130  and is in air flow communication with the passenger compartment  205  of the transit vehicle  200  through a return air opening  215  passing through the roof  202  of the transit vehicle  200  and a pair of supply air openings  213 ,  217  passing through the roof  202  of the transit vehicle  200 . The return air opening  215  is centrally located between the pair of supply air openings  213 ,  217  with the first supply air opening  213  being located outboard of the return air opening  215  on the curbside thereof and with the second supply air opening  217  being located outboard of the return air opening  215  on the roadside thereof. The set of evaporator coils  122  includes a first longitudinally extending evaporator coil  122 C and a second longitudinally extending evaporator coil  122 R, both disposed within the evaporator module  120  and connected in refrigerant flow communication with the condenser coils via the refrigerant circuit. 
     In operation, the at least one evaporator fan  124  circulates air from the passenger compartment  205  through the return air opening  215 , thence through the evaporator coils  122 C,  122 R, and back to the passenger compartment  205  as conditioned supply air through the first and second supply air openings  213 ,  217 . In the depicted embodiment, the at least one evaporator fan  124  comprises a first plurality of fans  124 C arrayed in a longitudinally extending row outboard of and in operative association with the first evaporator coil  122 C and a second plurality of fans  124 R arrayed in a longitudinally extending row outboard of and in operative association with the second evaporator coil  122 R. The at least one evaporator fan  124 , that is the first plurality of fans  124 C and the second plurality of fans  124 R, operate to draw return air from the passenger compartment  205  through the return air opening  215 . The first plurality of fans  124 C draws a first portion of that return air through the first evaporator coil  122 C to be cooled as it passes in heat exchange relationship with the refrigerant circulating through the first evaporator coil  122 C and thence supplies the conditioned air back to the passenger compartment  205  through the first supply air opening  213 . Similarly, the second plurality of fans  124 R draws a second portion of that return air through the second evaporator coil  122 R to be cooled as it passes in heat exchange relationship with the refrigerant circulating through the second evaporator coil  122 R and thence supplies the conditioned air back to the passenger compartment  205  through the second supply air opening  217 . 
     In the depicted embodiment, the first plurality of fans  124 C comprise squirrel cage blowers disposed in juxtaposition with the first supply air opening  213  so as to discharge conditioned air downwardly through the first supply air opening  213 , and the second plurality of fans  124 R comprise squirrel cage blowers disposed in juxtaposition with the second supply air opening  217  so as to discharge conditioned air downwardly through the second supply air opening  217 . However, it is to be understood that throughout this application, the term fan is used in the generic sense to refer to fans or blowers, whether of the axial, centrifugal, squirrel cage, or other type, as well as other types of air movers, whether used in connection with the evaporator module  120  and the condenser module  130 . 
     The roof  202  of the bus  200  covers the passenger compartment  205  and has a longitudinal expanse extending along the longitudinal axis of the bus  200  between the front and back of the passenger compartment  205  and a lateral expanse extending transversely to the longitudinal axis of the bus  200  between the side walls  220  of the passenger compartment  205 . Referring now to  FIGS. 4 and 5 , the air conditioning system includes a three-piece airflow management arrangement including a first supply air discharge plenum housing  140 , a second supply air discharge plenum housing  150 , and a return air grill assembly  160  on the passenger compartment ceiling side  212  of the roof  202 . The first and second supply air discharge plenum housings  140 ,  150 , which formed a supply air plenum arrangement, are disposed on opposite sides of the longitudinal axis and in spaced relationship, equally spaced from the longitudinal axis of the transit vehicle  200 . The first supply air discharge plenum housing  140  is disposed in juxtaposition with the first supply air opening  213  and defines a plenum  145  for receiving the supply air passing from the evaporator module  120  through the first supply air opening  213 . The second supply air discharge plenum housing  150  is disposed in juxtaposition with the second supply air opening  217  and defines a plenum  155  for receiving the supply air passing from the evaporator module  120  through the second supply air opening  217 . 
     Each of the first supply air discharge plenum housing  140  and the second supply air discharge plenum housing  150  have at least one air outlet  182 ,  184 ,  186  therein establishing air flow communication between the discharge air plenum,  145 ,  155 , respectively, and the passenger compartment  205 . In the depicted embodiment, as best seen in  FIG. 5-9 , the first supply air discharge plenum housing  140  has a pair of air outlets  182  in the floor panel  172  thereof at each end of the floor panel, a pair of air outlets  184  at each end of each of the longitudinally extending side walls  174 , and at least one air outlet  186  in each of the laterally extending side walls  176 . Similarly, the second supply air discharge plenum housing  150  has a pair of air outlets  182  in the floor panel  172  thereof at each end of the floor panel, a pair of air outlets  184  at each end of each of the longitudinally extending side walls  174 , and at least one air outlet  186  in each of the laterally extending side walls  176 . The air outlets  182 ,  184 ,  186  may include a set of louvers or flow guides  188  for directing the supply air discharging therethrough from the respective plenums  145 ,  155  into the passenger compartment  205 . The louvers or guide members, which for purposes of illustration are shown in detail in  FIG. 5  only with respect to the air outlets  182  but may also be installed in air outlets  184  (see  FIG. 4 ) and air outlets  186 , may be selectively positionable or fixed positioned. The return air grille assembly  160  includes generally rectangular frame  164  having a central laterally extending member  166  and supporting a pair of grillwork panels  162  through which return air drawn from the passenger compartment  205  passes into the return air opening  215 . 
     The return air grille assembly  160  is disposed centrally between the first supply air discharge plenum housing  140  and the second supply air discharge housing  150  in juxtaposition with and beneath the return air opening  215  in the roof  210 . The first and second supply air discharge plenum housings  140  and  150  have a relatively low profile and the return air grille assembly has a very low profile. By relatively low profile, it is meant that the first and second supply air discharge plenum housings extend downwardly from the ceiling  212  into the passenger compartment  205  by a maximum depth of three inches (7.6 centimeters) or less. By a very low profile, it is meant that the return air grille assembly  160  extends downwardly from the ceiling  212  into the passenger compartment  205  by a maximum depth of about one inch (about 2.5 centimeters). Thus, in comparison to the aforementioned prior art generally rectangular, toroidal-like, one-piece housings of the prior art that typically extend downwardly into the passenger compartment from three to five inches (7.6 to 12.7 centimeters) across the entire width of the housing, including over the center aisle, passenger headroom is increased particularly over the center aisle where the return air grille assembly  60  extends downwardly into the passenger compartment by less than about one inch about 2.54 centimeter). The resultant increase in headroom due to the very low profile of the return air grill assembly  160  over the center aisle is highly desirable as it facilitates movement of passengers along the center aisle. 
     Referring now to  FIGS. 5-9 , respectively, an exemplary embodiment of the supply air discharge plenum housing  140 ,  150  are shown in a perspective view, a plan view, a longitudinal side elevation view and a lateral side wall elevation view. It should be noted that the views shown in  FIGS. 7-9  are not drawn to a common scale, the view in  FIG. 9  being enlarged for illustration purposes relative to the views shown in  FIGS. 7 and 8 . The first and second supply air discharge plenum housings  140 ,  150  may include a generally rectangular upper perimetral flange  170 , a lower floor panel  172  disposed in spaced relationship below the perimetral flange  170 , a pair of longitudinally extending side walls  174  depending from opposite longitudinal sides of the perimetral flange  170  to opposite longitudinal sides of the floor panel  172 , and a pair of laterally extending side walls  176  depending from opposite lateral sides of the perimetral flange  170  to opposite lateral sides of the floor panel  172 . In an embodiment, each of the side walls  174 ,  176  depends inwardly from the upper perimetral flange at an included angle, A, of about 45 degrees. 
     At least one of the floor panel  172  and the side walls  174 ,  176  has at least one air outlet opening therein. In depicted exemplary embodiment, the floor panel  172  has a pair of air outlets  182  opening therethrough in each of the longitudinal ends of the floor panel, each of the longitudinally extending side walls has a pair of air outlets  184  opening therethrough at each longitudinal end thereof, and the laterally extending side walls side has at least one air outlet  186  opening therethrough. A plurality of mounting holes  178  may be provided in the perimetral flange  170  at spaced intervals about the perimeter of the flange  170  through which bolts, screws or other fasteners (not shown) may be inserted for securing the supply air discharge plenum housing  140 ,  150  to the ceiling  212  of the transit vehicle  200 . 
     It should be noted that, in the exemplary embodiment depicted in  FIGS. 5-9 , the first and second supply air discharge plenum housings  140 ,  150  are interchangeable relative to each other. Additionally, due to the relatively narrow width, that is the lateral dimension, of the supply air discharge plenum housings  140 ,  150 , compared to the width of the passenger compartment  205  of the transit vehicle  200 , the supply air discharge plenum housings  140 ,  150  may generally be interchanged from one vehicle to another vehicle requiring supply air discharge plenum housings of the same length, irrespective of the particular contour of the roof of the vehicle  200 . Typically, the supply air discharge plenum housings  140 ,  150  has a width, that is a lateral dimension, of about fifteen (15) inches (about 37 centimeters) and a length, that is a longitudinal dimension, of about three (3) to six (6) feet (about meters to about meters). As noted previously, the supply air discharge plenum housings  140 ,  150  are low profile in that the depth, D, of thereof is less than a three inches (about 7.6 centimeters). 
     The terminology used herein is for the purpose of description, not limitation. Specific structural and functional details disclosed herein are not to be interpreted as limiting, but merely as basis for teaching one skilled in the art to employ the present invention. While the present invention has been particularly shown and described with reference to the exemplary embodiments as illustrated in the drawing, it will be recognized by those skilled in the art that various modifications may be made without departing from the spirit and scope of the invention. Those skilled in the art will also recognize the equivalents that may be substituted for elements described with reference to the exemplary embodiments disclosed herein without departing from the scope of the present invention. 
     Therefore, it is intended that the present disclosure not be limited to the particular embodiment(s) disclosed as, but that the disclosure will include all embodiments falling within the scope of the appended claims.