Centrifugal fan

Abstract

A centrifugal fan includes a hub, a plurality of blades, and a shroud. The blades each have a curved part that is curved to incline toward a side on which air impinges when a connected end connected to an inwardly protruding portion of the shroud moves in a rotating direction of the centrifugal fan. The hub includes a hub-side diffuser ring that protrudes radially outward of the blades. The shroud includes a shroud-side diffuser ring that protrudes radially outward of the blades.

1 . A centrifugal fan comprising:
 a hub;   a plurality of blades arranged along a circumferential direction of the hub; and   a shroud arranged on an opposite side of the blades from the hub,   each of the blades having a curved part that is curved to incline toward a side on which air impinges when a connected end connected to an inwardly protruding portion of the shroud moves in a rotating direction of the centrifugal fan,   the hub having a hub-side diffuser ring that protrudes radially outward of the blades, and   the shroud having a shroud-side diffuser ring that protrudes radially outward of the blades.   
     
     
         2 . The centrifugal fan according to  claim 1 , wherein
 a hub-side end at a rear edge of each of the blades is positioned more forward in the rotating direction of the centrifugal fan than a shroud-side end of the rear edge.   
     
     
         3 . The centrifugal fan according to  claim 1 , wherein
 the hub-side diffuser ring and the shroud-side diffuser ring have outer diameters that are each at least 1.1 times larger than a diameter of a circumscribed circle of the plurality of blades.   
     
     
         4 . The centrifugal fan according to  claim 1 , wherein
 the shroud-side diffuser ring includes a portion linearly extending in a radial direction of the centrifugal fan continuously from an edge of the shroud.   
     
     
         5 . The centrifugal fan according to  claim 1 , wherein
 the shroud-side diffuser ring includes a portion bent in an axial direction of the centrifugal fan away from the hub-side diffuser ring, and the hub-side diffuser ring extends in a radial direction of the centrifugal fan.   
     
     
         6 . The centrifugal fan according to  claim 2 , wherein
 the hub-side diffuser ring and the shroud-side diffuser ring have outer diameters that are each at least 1.1 times larger than a diameter of a circumscribed circle of the plurality of blades.   
     
     
         7 . The centrifugal fan according to  claim 2 , wherein
 the shroud-side diffuser ring includes a portion linearly extending in a radial direction of the centrifugal fan continuously from an edge of the shroud.   
     
     
         8 . The centrifugal fan according to  claim 3 , wherein
 the shroud-side diffuser ring includes a portion linearly extending in a radial direction of the centrifugal fan continuously from an edge of the shroud.   
     
     
         9 . The centrifugal fan according to  claim 6 , wherein
 the shroud-side diffuser ring includes a portion linearly extending in a radial direction of the centrifugal fan continuously from an edge of the shroud.   
     
     
         10 . The centrifugal fan according to  claim 2 , wherein
 the shroud-side diffuser ring includes a portion bent in an axial direction of the centrifugal fan away from the hub-side diffuser ring, and the hub-side diffuser ring extends in a radial direction of the centrifugal fan.   
     
     
         11 . The centrifugal fan according to  claim 3 , wherein
 the shroud-side diffuser ring includes a portion bent in an axial direction of the centrifugal fan away from the hub-side diffuser ring, and the hub-side diffuser ring extends in a radial direction of the centrifugal fan.   
     
     
         12 . The centrifugal fan according to  claim 4 , wherein
 the shroud-side diffuser ring includes a portion bent in an axial direction of the centrifugal fan away from the hub-side diffuser ring, and the hub-side diffuser ring extends in a radial direction of the centrifugal fan.   
     
     
         13 . The centrifugal fan according to  claim 6 , wherein
 the shroud-side diffuser ring includes a portion bent in an axial direction of the centrifugal fan away from the hub-side diffuser ring, and the hub-side diffuser ring extends in a radial direction of the centrifugal fan.   
     
     
         14 . The centrifugal fan according to  claim 7 , wherein
 the shroud-side diffuser ring includes a portion bent in an axial direction of the centrifugal fan away from the hub-side diffuser ring, and the hub-side diffuser ring extends in a radial direction of the centrifugal fan.   
     
     
         15 . The centrifugal fan according to  claim 8 , wherein
 the shroud-side diffuser ring includes a portion bent in an axial direction of the centrifugal fan away from the hub-side diffuser ring, and the hub-side diffuser ring extends in a radial direction of the centrifugal fan.   
     
     
         16 . The centrifugal fan according to  claim 9 , wherein
 the shroud-side diffuser ring includes a portion bent in an axial direction of the centrifugal fan away from the hub-side diffuser ring, and the hub-side diffuser ring extends in a radial direction of the centrifugal fan.