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Patent Searching and Data

Document Type and Number:
Japanese Patent JP2005291149
Kind Code:

To dissolve a problem that although there is a technique of arranging fin pitch angles unequally and offsetting positions of fins on a front and a back surface by a half pitch as a technique for reducing fan noise, an overall value of the noise in an audible frequency range to human beings is not reduced.

When a number of fins 21a is represented as N and a rotation speed of an electric motor 1 is represented as S (revolution number/sec), a value calculated by N×S is set higher than the audible frequency range of human beings. This causes a primary peak of the fan noise to be generated in a high range outside the audio frequency range and the fan noise audible to human beings can be reduced. All the fin pitch angles are set equally and the primary peak of the fan noise does not change. The number of the fins 21a is set to be a prime number and the primary and secondary peaks and the like are not generated in the audible frequency range. A slope portion is formed at a terminal end of a swirl chamber 28 for gradually decreasing a volume space and the fan noise when the primary peak of the fan noise passes through the audible frequency range can be reduced.

Tsuzuki, Kunihiro
Yokoyama, Shinichi
Uchida, Akikazu
Application Number:
Publication Date:
October 20, 2005
Filing Date:
April 02, 2004
Export Citation:
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International Classes:
F04D29/38; F01D5/10; F04D23/00; F04D29/44; F04D29/66; (IPC1-7): F04D29/66; F04D29/38; F04D29/44
Attorney, Agent or Firm:
石黒 健二