Centrifugal blower

Abstract

The inside of a blower casing of a centrifugal blower includes a discharge airflow path, which extends outward in a radial direction of a rotating shaft, on an airflow downstream side from a trailing edge of each of blades of a centrifugal fan. The discharge airflow path includes an adjacent airflow path adjacent to the trailing edge of each blade. When the length in the axial direction of the blade at the trailing edge is assumed to be blade height, and when the length in the axial direction at the trailing edge of the centrifugal fan is assumed to be fan height, the length in the axial direction of the adjacent airflow path is equal to or larger than the blade height and equal to or smaller than the fan height.

What is claimed is: 
     
         1 .- 10 . (canceled) 
     
     
         11 . A centrifugal blower for blowing air, comprising:
 a centrifugal fan that sucks air from one side of a rotating shaft in its axial direction and discharges the air radially outward of the rotating shaft; and   a blower casing that accommodates the centrifugal fan and opens along an entire circumference of the blower casing around the rotating shaft, wherein:   the centrifugal fan includes:
 a plurality of blades arranged side by side in a circumferential direction of the rotating shaft; 
 a shroud that connects together one sides of the plurality of blades in the axial direction; and 
 a main plate that connects together the other sides of the plurality of blades in the axial direction and is connected to the rotating shaft; 
   the blower casing includes therein a discharge airflow path, which extends radially outward of the rotating shaft, on an airflow downstream side of a trailing edge of each of the plurality of blades;   the discharge airflow path includes an adjacent airflow path adjacent to the trailing edge of each of the plurality of blades; and   provided that:
 a length of the trailing edge of each of the plurality of blades in the axial direction is a blade height; and 
 a length of the centrifugal fan at the trailing edge in the axial direction is a fan height, 
   a length of the adjacent airflow path in the axial direction is equal to or larger than the blade height, and is equal to or smaller than the fan height.   
     
     
         12 . The centrifugal blower according to  claim 11 , wherein the adjacent airflow path is an airflow path defined by a pair of wall portions of the blower casing that are opposed to each other in the axial direction. 
     
     
         13 . The centrifugal blower according to  claim 11 , wherein:
 one member of the shroud and the main plate includes an extending portion that extends radially outward of the trailing edge of each of the plurality of blades;   the blower casing includes a pair of wall portions opposed to each other in the axial direction; and   the adjacent airflow path is an airflow path defined by the extending portion and one of the pair of wall portions.   
     
     
         14 . The centrifugal blower according to  claim 13 , wherein:
 the one member is the main plate; and   the adjacent airflow path is an airflow path defined by the extending portion of the main plate, and a wall portion of the pair of wall portions that is closer to the shroud than to the main plate.   
     
     
         15 . The centrifugal blower according to  claim 13 , wherein:
 the one member is the shroud; and   the adjacent airflow path is an airflow path defined by the extending portion of the shroud, and a wall portion of the pair of wall portions that is closer to the main plate than to the shroud.   
     
     
         16 . The centrifugal blower according to  claim 11 , wherein:
 the shroud includes a first extending portion that extends radially outward of the trailing edge of each of the plurality of blades;   the main plate includes a second extending portion that extends radially outward of the trailing edge of each of the plurality of blades; and   the adjacent airflow path is an airflow path defined by the first extending portion and the second extending portion.   
     
     
         17 . The centrifugal blower according to  claim 11 , further comprising an electric motor that rotates the centrifugal fan, wherein the electric motor is disposed on a back side of a surface of the main plate that is opposed to the plurality of blades and the shroud. 
     
     
         18 . The centrifugal blower according to  claim 11 , wherein a length of the discharge airflow path in the axial direction becomes larger toward the airflow downstream side. 
     
     
         19 . The centrifugal blower according to  claim 18 , wherein the length of the discharge airflow path in the axial direction is set to be equal to or smaller than a maximum length of the centrifugal fan in the axial direction. 
     
     
         20 . A centrifugal blower for blowing air, comprising:
 a centrifugal fan that sucks air from one side of a rotating shaft in its axial direction and discharges the air radially outward of the rotating shaft; and   a blower casing that accommodates the centrifugal fan and opens along an entire circumference of the blower casing around the rotating shaft, wherein:   the centrifugal fan includes:
 a plurality of blades arranged side by side in a circumferential direction of the rotating shaft; 
 a shroud that connects together one sides of the plurality of blades in the axial direction; and 
 a main plate that connects together the other sides of the plurality of blades in the axial direction and is connected to the rotating shaft; 
   the blower casing includes therein a discharge airflow path, which extends radially outward of the rotating shaft, on an airflow downstream side of a trailing edge of each of the plurality of blades;   the discharge airflow path includes an adjacent airflow path adjacent to the trailing edge of each of the plurality of blades; and   provided that:
 a length of the discharge airflow path in the axial direction at a position closest to the trailing edge of each of the plurality of blades is an airflow path height; 
 a length of the trailing edge of each of the plurality of blades in the axial direction is a blade height; and 
 a length of the centrifugal fan at the trailing edge in the axial direction is a fan height, 
   the airflow path height of the adjacent airflow path is equal to or larger than the blade height, and is equal to or smaller than the fan height.   
     
     
         21 . The centrifugal blower according to  claim 20 , wherein the adjacent airflow path is an airflow path defined by a pair of wall portions of the blower casing that are opposed to each other in the axial direction. 
     
     
         22 . The centrifugal blower according to  claim 20 , wherein:
 one member of the shroud and the main plate includes an extending portion that extends radially outward of the trailing edge of each of the plurality of blades;   the blower casing includes a pair of wall portions opposed to each other in the axial direction; and   the adjacent airflow path is an airflow path defined by the extending portion and one of the pair of wall portions.   
     
     
         23 . The centrifugal blower according to  claim 22 , wherein:
 the one member is the main plate; and   the adjacent airflow path is an airflow path defined by the extending portion of the main plate, and a wall portion of the pair of wall portions that is closer to the shroud than to the main plate.   
     
     
         24 . The centrifugal blower according to  claim 22 , wherein:
 the one member is the shroud; and   the adjacent airflow path is an airflow path defined by the extending portion of the shroud, and a wall portion of the pair of wall portions that is closer to the main plate than to the shroud.   
     
     
         25 . The centrifugal blower according to  claim 20 , wherein:
 the shroud includes a first extending portion that extends radially outward of the trailing edge of each of the plurality of blades;   the main plate includes a second extending portion that extends radially outward of the trailing edge of each of the plurality of blades; and   the adjacent airflow path is an airflow path defined by the first extending portion and the second extending portion.   
     
     
         26 . The centrifugal blower according to  claim 20 , further comprising an electric motor that rotates the centrifugal fan, wherein the electric motor is disposed on a back side of a surface of the main plate that is opposed to the plurality of blades and the shroud. 
     
     
         27 . The centrifugal blower according to  claim 20 , wherein a length of the discharge airflow path in the axial direction becomes larger toward the airflow downstream side. 
     
     
         28 . The centrifugal blower according to  claim 27 , wherein the length of the discharge airflow path in the axial direction is set to be equal to or smaller than a maximum length of the centrifugal fan in the axial direction.