Centrifugal Blower

Abstract

A centrifugal blower includes a centrifugal fan and a partition cylinder portion. The centrifugal fan includes first blades and second blades arranged about a fan central axis. The partition cylinder portion has a cylindrical shape extending in an axial direction. A diameter of the partition cylinder portion expands in the axial direction. The partition cylinder portion is located inside the second blades in the radial direction. The partition cylinder portion partitions, on an airflow upstream side of the first blades and the second blades, air drawn into spaces between the first blades from air drawn into spaces between the second blades. A length of each first blade in the radial direction is larger than a length of each second blade in the radial direction.

What is claimed is: 
     
         1 . A centrifugal blower comprising:
 a centrifugal fan including
 a plurality of first blades arranged about a fan central axis, and 
 a plurality of second blades arranged about the fan central axis, the plurality of second blades being located on a first side of the plurality of first blades in an axial direction of the fan central axis and being aligned to the plurality of first blades; and 
   a partition cylinder portion having a cylindrical shape extending in the axial direction, a diameter of the partition cylinder portion expanding in the axial direction toward a second side that is an opposite side of the first side, the partition cylinder portion being located inside the plurality of second blades in a radial direction of the centrifugal fan, wherein   the centrifugal fan is configured to rotate about the fan central axis to
 take in air from the first side into spaces between the plurality of first blades and spaces between the plurality of second blades, 
 blow out the air in the spaces between the plurality of first blades outward in the radial direction, and 
 blow out the air in the spaces between the plurality of second blades outward in the radial direction, 
   the partition cylinder portion partitions, on an airflow upstream side of the plurality of first blades and the plurality of second blades, the air taken into the spaces between the plurality of first blades through an inside of the partition cylinder portion in the radial direction from the air taken into the spaces between the plurality of second blades through an outside of the partition cylinder portion in the radial direction, and   a length of each first blade of the plurality of first blades in the radial direction is larger than a length of each second blade of the plurality of second blades in the radial direction.   
     
     
         2 . The centrifugal blower according to  claim 1 , wherein
 an inner diameter of the plurality of first blades whose center is the fan central axis is smaller than an inner diameter of the plurality of second blades whose center is the fan central axis.   
     
     
         3 . The centrifugal blower according to  claim 1 , wherein
 an outer diameter of the plurality of second blades whose center is the fan central axis is smaller than an outer diameter of the plurality of first blades whose center is the fan central axis.   
     
     
         4 . The centrifugal blower according to  claim 1 , wherein
 the centrifugal fan includes a separation panel located between the plurality of first blades and the plurality of second blades, the separation panel having a plate shape extending in the radial direction, wherein   the separation panel partitions the air flowing through the spaces between the plurality of first blades from the air flowing through the spaces between the plurality of second blades.   
     
     
         5 . The centrifugal blower according to  claim 4 , wherein
 a radially inner part of the separation panel in the radial direction is joined to the partition cylinder portion,   the partition cylinder portion is configured to rotate together with the centrifugal fan, and   the partition cylinder portion extends inward in the radial direction from the separation panel.   
     
     
         6 . The centrifugal blower according to  claim 1 , wherein
 the partition cylinder portion is separated from the centrifugal fan and is a non-rotating member that is not configured to rotate.   
     
     
         7 . The centrifugal blower according to  claim 1 , wherein
 a number of the plurality of first blades is different from a number of the plurality of second blades.   
     
     
         8 . The centrifugal blower according to  claim 1 , wherein
 the each first blade is a backward-curved blade extending away from a rotation direction of the centrifugal fan toward an outer side of the each first blade in the radial direction.   
     
     
         9 . The centrifugal blower according to  claim 1 , wherein
 the each second blade is a forward-curved blade extending toward a rotation direction of the centrifugal fan toward an outer side of the each second blade in the radial direction.   
     
     
         10 . The centrifugal blower according to  claim 1 , wherein
 the each first blade has a first trailing edge located downstream in the each first blade with respect to an airflow in the spaces between the plurality of first blades,   the each second blade has a second trailing edge located downstream in the each second blade with respect to an airflow in the spaces between the plurality of second blades, and   a height of the first trailing edge in the axial direction is smaller than a height of the second trailing edge in the axial direction.   
     
     
         11 . The centrifugal blower according to  claim 1 , wherein
 the each first blade has a first leading edge located upstream in the each first blade with respect to an airflow in the spaces between the plurality of first blades,   the each second blade has a second leading edge located upstream in the each second blade with respect to an airflow in the spaces between the plurality of second blades, and   a height of the first leading edge in the axial direction is smaller than a height of the second leading edge in the axial direction.   
     
     
         12 . The centrifugal blower according to  claim 1 , further comprising:
 a fan casing that accommodates the centrifugal fan, the fan casing defining a fan surrounding space that surrounds the centrifugal fan outside the centrifugal fan in the radial direction, the air flowing into the fan surrounding space from the centrifugal fan; and   a partition panel that partitions the fan surrounding space in the axial direction into a first flow-out passage and a second flow-out passage, wherein   a first air flowing out of the spaces between the plurality of first blades flows into the first flow-out passage,   a second air flowing out of the spaces between the plurality of second blades flows into the second flow-out passage, and   the partition panel is configured to limit the first air from entering the second flow-out passage and limit the second air from entering the first flow-out passage.   
     
     
         13 . The centrifugal blower according to  claim 1 , further comprising:
 a filter located on a first side of the partition cylinder portion in the axial direction to filtrate the air flowing toward the centrifugal fan, wherein
 the partition cylinder portion extends to the filter. 
   
     
     
         14 . The centrifugal blower according to  claim 1 , further comprising:
 an upstream partition wall located on a first side of the partition cylinder portion in the axial direction and separated from the partition cylinder portion, the upstream partition wall having a cylindrical shape aligned to the partition cylinder portion in the axial direction, the upstream partition wall partitioning the air flowing into the inside of the partition cylinder portion from the air flowing into the outside of the partition cylinder portion on an airflow upstream side of the partition cylinder portion; and   a filter located on a first side of the upstream partition wall in the axial direction to filtrate the air flowing toward the centrifugal fan, wherein   the upstream partition wall extends to the filter.