Centrifugal fan, and fan equipped with sound-muffling box and using centrifugal fan

Abstract

Centrifugal fan includes casing and impeller, and discharge duct is connected to casing. At least one of tongue-part-side wall surface on tongue part side extending from casing outlet of casing and opposite tongue-part-side wall surface on side opposite to tongue part side extending from casing outlet protrudes into the inside of discharge duct, and outlet gas flow is bent at predetermined angle and is formed into discharge duct internal gas flow.

1 . A centrifugal fan comprising:
 a casing having a scroll; and   an impeller disposed inside the casing,   wherein   the casing includes a side plate having a suction port,   the scroll includes an outlet; and   the casing is connected to an discharge duct,   an outlet gas flow which flows through the outlet is parallel to a plane orthogonal to a rotation axis of the impeller,   at least one of a tongue-part-side wall surface on a tongue part side and an opposite tongue-part-side wall surface on another side opposite to the tongue part side extending from the casing outlet of the casing protrudes into the discharge duct, and   as viewed from a direction orthogonal to the suction port, the outlet gas flow is bent from the tongue part side toward the side opposite to the tongue part side at a predetermined angle, and formed into an internal gas flow which flows through the discharge duct.   
     
     
         2 . The centrifugal fan according to  claim 1 , wherein the predetermined angle is larger than 0 degree and smaller than 45 degrees. 
     
     
         3 . The centrifugal fan according to  claim 1 , wherein an open end of the tongue-part-side wall surface is in contact with a wall surface of the discharge duct when the tongue-part-side wall surface protrudes into the discharge duct. 
     
     
         4 . The centrifugal fan according to  claim 1 , wherein a gap is formed between a tongue-part-side wall surface side and the discharge duct when the tongue-part-side wall surface protrudes into the discharge duct. 
     
     
         5 . The centrifugal fan according to  claim 4 , wherein a width of the tongue-part-side wall surface is equal to a width of the impeller. 
     
     
         6 . The centrifugal fan according to  claim 1 , wherein a connection portion on the side opposite to the tongue part side between the casing and the discharge duct is closer to the impeller than a tongue part facing position at which a perpendicular extending downwardly to the opposite tongue-part-side wall surface from the tongue part intersects. 
     
     
         7 . The centrifugal fan according to  claim 1  further comprising an discharge adapter which covers the casing outlet,
 wherein the discharge duct and the discharge adapter are connected to each other, and the tongue-part-side wall surface and the opposite tongue-part-side wall surface protrude into the discharge adapter. 
 
     
     
         8 . The centrifugal fan according to the  claim 7 , wherein a sound absorbing member is interposed between an discharge adapter inner surface and the tongue-part-side wall surface and between the discharge adapter inner surface and the opposite tongue-part-side wall surface. 
     
     
         9 . The centrifugal fan according to the  claim 8 , wherein a plurality of small holes are formed in the tongue-part-side wall surface and the opposite tongue-part-side wall surface. 
     
     
         10 . The centrifugal fan according to the  claim 7 , wherein a center axis of an opening of the discharge adapter passes the rotation axis. 
     
     
         11 . A fan equipped with a sound-muffling box, the fan comprising:
 the centrifugal fan described in  claim 1 ; and   a body in which the centrifugal fan is incorporated,   wherein   the body includes:
 an outlet panel provided with a body blowout port and an discharge adapter; 
 a suction panel provided with a body suction port and a suction adapter; and 
 a side panel to which a checkup panel is fixed, 
   the discharge adapter is connected to the discharge duct such that the casing outlet is in communication with the discharge duct,   the discharge adapter is disposed at a center of the outlet panel, and   the suction adapter is disposed at a center of the suction panel.   
     
     
         12 . The fan equipped with a sound-muffling box according to  claim 11 , wherein the body blowout port is disposed at the center of the outlet panel. 
     
     
         13 . The fan equipped with a sound-muffling box according to the  claim 11 , wherein the outlet panel is in contact with the casing outlet.