Patent ID: 9574569
Date: 2017-02-21
CPC Classifications: F04D

Claim:
1. A recirculation fan, comprising: a casing; a covering member coupled with said casing to define an accommodation space; a wind-guiding device disposed on said covering member, and comprising a wind-guiding cover and a magnetoresistive structure, wherein said magnetoresistive structure is disposed on said covering member and said wind-guiding cover, said magnetoresistive structure comprises at least one first magnetic member and at least one second magnetic member, and said first magnetic member and said second magnetic member are disposed between said wind-guiding cover and said covering member, and wherein one of said first magnetic member and said second magnetic member is a permanent magnet, and the other one of said first magnetic member and said second magnetic member is a magnetic conductor; a passive impeller disposed within said accommodation space; and an active impeller disposed within said accommodation space and located beside said passive impeller for generating a wind to drive rotation of said passive impeller and said wind-guiding cover, wherein said covering member is disposed between said wind-guiding cover and said active impeller, and wherein in response to a magnetic torque resulted from a magnetic vortex of said magnetoresistive structure, a rotating speed of said wind-guiding cover is slowed down.