SCROLL CASE FOR USE OF BLOWER UNIT

PURPOSE: A scroll case for use of blower unit is provided to reduce a lower-frequency noise and increase air flow rate by changing the structure of a cutoff. CONSTITUTION: A scroll case comprises a scroll portion(1) having at a center thereof a centrifugal fan(2), and a blast inlet(3) extended toward an outlet of the scroll portion in such a manner as to be communicated with the scroll portion, wherein the scroll portion is formed as a 10 degree logarithmic scroll line gradually decreasing along a periphery of the centrifugal fan in counter-clockwise direction having a portion where the scroll portion and a guide wall(31) meets, as a scroll end point of 360 degree. In a scroll case for a blower unit having 64 degree as an angle of a cutoff(11), a cutoff extension portion is extended from the cutoff in such a manner as to be parallel with the outer periphery of the centrifugal fan. Preferably, the extension length of the cutoff extension portion is 40 to 58mm. Preferably, the cutoff extension bands have width tapered as it goes from the cutoff toward ends of the bands.