Centrifugal blower

A centrifugal blower, in which a centrifugal fan is rotatable about a fan central axis to suction air in an axial direction of the fan central axis and discharge the suctioned air in a radial direction of the fan central axis, the centrifugal blower comprising:

• the centrifugal fan that includes:
• a plurality of blades that are circumferentially arranged one after another about the fan central axis;
• and
• a shroud ring that is shaped into a plate form and is connected to a part of each of the plurality of blades located on one side in the axial direction, wherein the shroud ring includes a fan suction hole that is configured to suction the air;
• and
• a case that receives the centrifugal fan and has a case suction hole that is located on the one side in the axial direction and is configured to suction the air, wherein:
• the case includes a cover portion that covers a surface of the shroud ring, which is located on the one side in the axial direction;
• the cover portion includes:
• a cover opposing that is opposed to the shroud ring;
• and
• a recess that is formed in the cover opposing surface and is shaped in a form of a circle, which has a center positioned at the fan central axis;
• the shroud ring includes:
• a ring opposing surface that is opposed to the cover portion;
• and
• at least one projection that is formed in at least a part of a region of the ring opposing surface, which is opposed to the recess;
• a gap is formed between the cover portion and the shroud ring in a state where the projection is placed in an inside of the recess;
• a shortest distance between a radially inner end part of the shroud ring and the cover portion is set to be larger than a shortest distance between a surface of the projection and a surface of the recess;
• an outer shortest distance is defined as a shortest distance between a radially outer surface part of the surface of the projection and the surface of the recess in the radial direction and is set to be smaller than a shortest distance between the surface of the projection and the surface of the recess in the axial direction;
• and
• an inner shortest distance is defined as a shortest distance between a radially inner surface part of the surface of the projection and the surface of the recess in the radial direction and is set to be smaller than the outer shortest distance.