| CPC F04D 17/16 (2013.01) [F04D 29/4226 (2013.01); F04D 29/663 (2013.01)] | 6 Claims |
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1. A centrifugal blower, comprising:
an impeller; and
a scroll casing accommodating the impeller,
the impeller being configured to draw in gas through an opening in a side surface and send out the gas in a centrifugal direction thereof,
the scroll casing including
an inlet that draws in the gas,
an outlet that blows out the gas sent out from the impeller,
a peripheral wall arranged along an outer circumference of the impeller, and
a tongue that guides the gas flowing along the peripheral wall to the outlet, the peripheral wall of the scroll casing including
a first planar portion extending continuously from the tongue, and
a second planar portion located at a position advanced from the first planar portion in a rotation direction of the impeller,
the peripheral wall being configured so that a clearance is minimal at the second planar portion, the clearance being a difference between
a distance from a center of the impeller to an inner surface of the peripheral wall, and
a distance from the center of the impeller to an outer surface of the impeller in a passage along the peripheral wall, and
with respect to the clearance
when a first clearance is defined as a value obtained by subtracting a radius of the impeller from a length of a first perpendicular line extending from the center of the impeller to the first planar portion, and
when a second clearance is defined as a value obtained by subtracting the radius of the impeller from a length of a second perpendicular line extending from the center of the impeller to the second planar portion,
a ratio of the first clearance to the second clearance being in a range from 1.5 to 2.5, inclusive.
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