| 摘要 |
PURPOSE:To eliminate noise generated in the captioned blower, by providing a mixed flow fan, a cylinder which has a diameter approximately similar to the fan and is positioned at the expansion part, and an orifice extended outward from this cylinder and fixed on the fan. CONSTITUTION:A motor 4 and a mixer flow fan 5 are provided in the small diameter conical part 2 of a duct 1 composed of said small diameter conical part 2 and a large diameter expansion part 3. A cylinder 7 is supported by an impeller 8, wherein the diameter of the cylinder 7 is approximately similar to that of the intake port of the conical orifice 6 which is provided to the outer periphery of the mixed flow fan 5 and is extended to the extent of the expansion part 3. When static pressure becomes high on operation, the part of discharged air counter-flows into the expansion part 3 through the gap 10 formed by the conical orifice 6 and the duct 1. With this arrangement, there is not happened the collision of an intake air flow with a counter air flow, and thereby it is possible to prevent the blower from generating noise.
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