Centrifugal blower has an Archimedean, or logarithmic spiral casing, with the scroll start point and end point situated on the same line, so that the scroll angle varies from 0 - 360 degrees

摘要

The centrifugal blower comprises a Sirocco fan having a number of blowing fans (22), and a scroll casing (24) forming a spiral draft passage at an external side of the fan. The fan is so mounted that spiral centers (0203) comprising the draft passage of the scroll casing are detached from a center (01) of the Sirocco fan at a predetermined distance such that a spiral curve of the scroll casing is simply changed to a non-linear curve to thereby enable to increase, a flow rate even at a low revolution of the fan and to reduce noise. The casing spiral is an Archimedean spiral or a logarithmic spiral. The distance (D) between the fan center and the spiral center of the spiral satisfies the formula: D is above zero, and below or equal to 0.15 Rp3, where Rp3 is a spiral radius of a scroll start point of the spiral.