Pivot Hood Assembly

Abstract

A pivot hood assembly ( 12 ) comprises a pair of identical hood pieces ( 14, 16 ) comprising a shell ( 20, 22 ) and a supporting frame assembly ( 24, 26 ). Each hood piece is attachable to a ventilation shaft ( 18 ) by an attachment framework ( 32 ) to which the hood pieces are pivotably attached. The hood pieces pivot between a closed position where inner edges ( 52 ) of each hood piece contact each other, and an open position where the inner edges ( 52 ) are spaced from each other to form an opening where the ventilation shaft is accessible.

1 . A pivot hood assembly ( 12 ) for a ventilation shaft ( 18 ), comprising: 
 a pair of hood pieces ( 14 ,  16 ), each hood piece comprising a shell ( 20 ,  22 ) having an inner edge ( 52 ), and a supporting frame assembly ( 24 ,  26 ); and    an attachment framework ( 32 ) adapted to be securely fixed to the ventilation shaft ( 18 ), each hood piece ( 14 ,  16 ) being pivotably mounted to the attachment framework ( 32 ) for movement between a closed position where the inner edges ( 52 ) contact each other and an open position where the inner edges ( 52 ) are spaced from each other to form an opening;    whereby when the attachment framework ( 32 ) is fixed to the ventilation shaft ( 18 ) and the hood pieces ( 14 ,  16 ) are pivoted to the closed position, the pivot hood assembly ( 12 ) is configured to control the flow of air entering or exiting the ventilation shaft ( 18 ), and when the hood pieces ( 14 ,  16 ) are pivoted to the open position, the ventilation shaft ( 18 ) is accessible through the opening.    
   
   
       2 . The pivot hood assembly ( 12 ) of  claim 1  wherein each hood piece ( 14 ,  16 ) is pivotably mounted to the attachment framework ( 32 ) at a balanced pivot point wherein little force is required to urge the hood piece to pivot.  
   
   
       3 . The pivot hood assembly ( 12 ) of claims  1  or  2  further comprising at least one closure device to secure the inner edges ( 52 ) to each other when the hood pieces ( 14 ,  16 ) are in the closed position.  
   
   
       4 . The pivot hood assembly ( 12 ) of any of claims  1 - 3  wherein the hood pieces ( 14 ,  16 ) are cooperatively linked so that movement of one hood piece will also move the other hood piece.  
   
   
       5 . The pivot hood assembly ( 12 ) of any of claims  1 - 4  further comprising at least one motor to move the pivot hoods between the open and closed positions.  
   
   
       6 . The pivot hood assembly ( 12 ) of any of claims  1 - 5  further comprising an air filter in each pivot hood.  
   
   
       7 . The pivot hood assembly ( 12 ) of any of claims  1 - 6  further comprising a screen in each pivot hood.  
   
   
       8 . The pivot hood assembly ( 12 ) of any of claims  1 - 7  mounted to the ventilation shaft ( 18 ) with the attachment framework ( 32 ) attached to the ventilation shaft at an upper end thereof so that when the hood pieces ( 14 ,  16 ) are in the closed position, the pivot hood assembly ( 12 ) has a portion extending below the ventilation shaft end.