Roof-mounted exhaust unit

Abstract

A roof-mounted exhaust unit including an inlet portion configured to receive exhaust air; an outlet portion through which the exhaust air exits the roof-mounted exhaust unit; a plurality of exhaust fans positioned downstream from the inlet and upstream from the outlet; a plurality of gravity dampers respectively associated with the exhaust fans, the gravity dampers positioned downstream from the exhaust fans and being configured to open when the exhaust air impacts the gravity dampers at a threshold velocity; and at least one acoustic absorbing panel configured to absorb sound produced by the roof-mounted exhaust unit.

What is claimed is: 
     
         1 . A roof-mounted exhaust unit, comprising:
 an inlet portion configured to receive exhaust air;   an outlet portion through which the exhaust air exits the roof-mounted exhaust unit;   a plurality of exhaust fans positioned downstream from the inlet and upstream from the outlet;   a plurality of gravity dampers respectively associated with the exhaust fans, the gravity dampers positioned downstream from the exhaust fans and being configured to open when the exhaust air impacts the gravity dampers at a threshold velocity; and   at least one acoustic absorbing panel configured to absorb sound produced by the roof-mounted exhaust unit.   
     
     
         2 . The roof-mounted exhaust unit of  claim 1 , wherein the plurality of exhaust fans comprise a two-by-two array of exhaust fans, wherein each of the exhaust fans is coupled to a respective gravity damper from the plurality of gravity dampers. 
     
     
         3 . The roof-mounted exhaust unit of  claim 1 , wherein each of the gravity dampers comprises a first door and a second door, wherein the first door is adjacent to the second door and the first door and second door are hinged along a center axis of an opening of a respective gravity damper. 
     
     
         4 . The roof-mounted exhaust unit of  claim 3 , wherein each of the gravity dampers further comprises at least one stopper that limits an opening of the first door and the second door to a maximum allowable angle. 
     
     
         5 . The roof-mounted exhaust unit of  claim 4 , wherein the maximum allowable angle is 62 degrees. 
     
     
         6 . The roof-mounted exhaust unit of  claim 3 , wherein the first door is lighter than the second door so that the first door opens when the exhaust air impacts the first door at a first velocity but the second door does not open when the exhaust air impacts the first door at the first velocity. 
     
     
         7 . The roof-mounted exhaust unit of  claim 1 , the exhaust fans are separated from each other by at least one divider panel, the at least one divider panel comprising an acoustic absorbing panel. 
     
     
         8 . The roof-mounted exhaust unit of  claim 1 , wherein each of the plurality of exhaust fans comprises a top panel positioned downstream from the plurality of fans, wherein the top panel is configured with an incline towards an outer edge of the roof-mounted exhaust unit. 
     
     
         9 . The roof-mounted exhaust unit of  claim 8 , wherein the top panel comprises a plurality of relief slots, the plurality of relief slots providing an airflow pathway external to the roof-mounted exhaust unit when the gravity dampers are in a closed position. 
     
     
         10 . The roof-mounted exhaust unit of  claim 1 , wherein an outer edge of the roof-mounted exhaust unit comprises at least one drainage slot positioned downstream from the plurality of exhaust fans, the at least drainage slot configured to drain liquids from the outlet portion. 
     
     
         11 . The roof-mounted exhaust unit of  claim 1 , further comprising a plurality of flow straighteners upstream from the plurality of exhaust fans, wherein each of the flow straighteners respectively corresponds to one of the plurality of exhaust fans. 
     
     
         12 . The roof-mounted exhaust unit of  claim 1 , further comprising a plurality of acoustic absorbing panels surrounding the outlet portion, wherein the plurality of acoustic absorbing panels are downstream from the exhaust fans. 
     
     
         13 . The roof-mounted exhaust unit of  claim 1 , further comprising each of the plurality of exhaust fans is associated with an access panel, wherein a respective exhaust fan is removable upon removal of the access panel. 
     
     
         14 . The roof-mounted exhaust unit of  claim 1 , each of the plurality of exhaust fans is installed on a lubricated rail and each of the plurality of exhaust fans is removal via the lubricated rail. 
     
     
         15 . The roof-mounted exhaust unit of  claim 1 , wherein the inlet portion comprises a first cross section and the outlet portion comprises a second cross section, wherein the first cross section is smaller than the second cross section. 
     
     
         16 . The roof-mounted exhaust unit of  claim 15 , further comprising a transition section, the transition section adapting the first cross section of the inlet portion to the second cross section of the outlet portion.